74
MINERAL RESOURCES OF PORTUGAL
Text prepared by
Luís Plácido Martins
CONTENTS
3
4 PREAMBLE
6 GEOLOGICAL AND MINING BACKGROUND
10 HISTORICAL OVERVIEW OF MINING IN PORTUGAL
25 PRECIOUS METALS
26 Galicia - Trás-os-Montes Zone
27 Central – Iberian Zone
29 South – Portuguese Zone
30 Secondary Deposits
32 BASE METALS
32 Ossa Morena Zone
35 South – Portuguese Zone
45 OTHER METALS
45 Tungsten and Tin
49 Uranium
52 Iron and Manganese
52 Lithium and High Tech Metals
54 Rare Earths
54 Nickel, Cobalt and Chrome
55 NON METALLIC MINERALS
55 1 - Rocks
60 2 - Industrial Minerals
66 LEGAL FRAMEWORK
67 Prospecting and Exploration Contract, and Mining Contract Regime
69 Mining Contracts
70 Doing Business in Portugal
71 KEY REFERENCES
4
Carlos A. A. Caxaria
Deputy General DirectorArea of Geological Resources
A complex and diversified geology endows Portu-gal with a considerable mineral potential, leading to the occurrence of considerable number of ore, industrial and ornamental stone deposits.
Mineral exploitation has a present considerable high level originated from world class deposits, as Neves-Corvo (Cu, Sn) and Panasqueira (W), but also from a lot of some other deposits producing salt, feldspar, kaolin, ball clay and fire clay, ornamental stones and some other mineral substances. Portu-gal is presently one of the main UE producers of copper, tin and tungsten concentrates and an im-portant world producer of ornamental stones.
Exploration activity is also at a high level consider-ing the relative small extent of the territory (rough-ly 90 000 Km2). Several international companies conduct exploration mainly focused on base and precious metals.
Portuguese territory covers half of the Iberian Py-rite Belt (IPB) which is considered the main met-allogenic province of the European Union, where occurrences of polymetallic massive sulphide de-posits like Neves-Corvo and Aljustrel, in Portugal, Rio Tinto, Sotiel, Los Frailes, Las Cruces, etc., in Spain. The IPB is the main primary source of base metals in the EU.
Hesperian granites and associated metamorphics in the north and central part of the country are as-sociated with tungsten and tin mineralisations.
The potential in precious metals is well known since ancient times and is spread out geographically all over the country, occurring in diverse forms and different geological settings (veins, skarns, shear
PREAMBLE
zones, placers, etc.).
The general framework of the activity has favour-able characteristics, which is considered one of the reasons, linked with the recognised mineral po-tential, of the present level of activity. Institutional stability, mineral rights granting mineral property, good infrastructure, incentives to investment, af-fordable qualified work for European standards, a light fiscal burden are several others reasons why activity is so interesting.
This publication lies in the framework of the public mission of the Direcção-Geral de Energia e Geolo-gia of promoting corporate investment, both na-tional and foreign, which may be complemented to all those interested with the provision of all the basic information about geology, hydrogeology, geophysics, geochemistry and drilling data in ar-chive or assistance in defining exploration targets and strategies.
You are welcome!
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The Hesperian Massif, in which predominantly metallic mineral resources occur, can in turn be divided into various geotectonic units, as described below (Ribeiro et al., 1979; Quesada, 1992): Galicia - Trás-os-Montes Zone - This is character-ised mainly by the existence of two mafic and ultramafic polymetamorphic massifs known as Bragança and Morais. The surrounding forma-tions date chiefly from the Silurian period and are characterised by the existence of acid and basic volcanic rock, which make contact with the massifs via larger thrust systems. Binary granite, “alkali” and porphyritic granite, biotite and “calcalkali” granite also occur. The chrome, platinum and, possibly, copper, nickel and co-balt potential of the Morais and Bragança mas-sifs is worth stressing, as is the potential for tungsten, tin, precious metals, uranium and, probably, polymetallic sulphides in the sur-rounding formations (Goínhas et al., 1992).
Central Iberian Zone - This is mainly character-ised by the predominance of the formations of the so-called Schist-Greywacke Complex, con-sisting of a flysch-type series dating from the Cambrian and Late Precambrian period. There are also large areas of “alkali” and “calcalkali” granitoids, in which various types of granite can be distinguished. Worth highlighting is the occurrence, in the Douro-Beiras sector, of continental formations from the Carboniferous period, where various coal mines have been ex-ploited (Douro Carboniferous Belt).
Also worth mentioning in this geotectonic unit are important mineralisations of tungsten and
tin, normally associated with the contact be-tween the granite and the metasediments, and the existence of precious metals, frequently as-sociated with arsenic and antimony, as in the Valongo/Gondomar Gold-Antimony Belt, for example. There are also important mineralisa-tions of uranium, many of which have been ex-ploited, related with late tectonic and metal-logenetic phenomena that have affected the post-tectonic “calcalkali” granite.
Ossa - Morena Zone - This is an extremely com-plex and diverse unit which begins with a poly-metamorphic Precambrian, followed by Cam-brian and Silurian formations, and ends with a flysch sequence from the Late Devonian period.
Contact with the Central Iberian Zone is carried out via an important shear zone which stretches from Oporto to Cordoba in Spain (Blastomylo-nitic Belt).
With regard to magmatism, the NE sector has a predominance of granitic rocks, chiefly “calcal-kali”, porphyritic, biotitic, similar to those in the north and centre.
To the south, the basic character of the intru-sions gradually increases, with “calcalkali” be-coming predominant: gabbros, diorites, ser-pentinites and anorthosites (which form the recently named Beja ophiolite complex), vari-ous different porphyries, and later intrusions comprising gabbrodiorites, granodiorites, to-nalites and granites (which constitute what is known as the Évora Massif ).
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The most important mineral occurrences are base metals, which are associated with the Cambrian-Ordovician volcanic sedimentary complex, pre-cious metals, chiefly related with the Precambrian formations, and tungsten and tin in the Sta. Eulália granitic complex, not to mention the potential for chrome, nickel, cobalt and platinum in the basic and ultrabasic rocks on the north and south mar-gins of this zone.
With regard to non-metallic minerals, this geotec-tonic unit is rich in ornamental rocks, particularly marble.
South Portuguese Zone - The Ossa - Morena Zone and this unit are joined by the Ferreira - Ficalho thrust (partially over the Beja-Acebuches complex), which runs approximately E-W to the east and NW-SE to the west.
The South - Portuguese Zone is characterised by the existence of a volcanic sedimentary complex (VS) from the Late Devonian - Early Carboniferous
period, overlain by a Culm flysch sequence; under-lying this complex is the so-called “Phyllite-Quartz-ite Group”. The oldest formations in this zone date from the Early Devonian period and belong to the “Pulo de Lobo” Formation, which includes phyllites, quartzites and rare acid and basic volcanic rocks. The acid volcanic rocks in the volcanic sedimentary complex constitutes the metallotect of the massive polymetallic sulphides that are characteristic of the Iberian Pyrite Belt, the most important metal-logenetic province in Portugal in which the Lousal, Aljustrel, Neves Corvo and S. Domingos mines are located.
We shall not go into the geological aspects of the Epi-Hercynian Covering, but shall touch on its non-metallic resources, namely sands, gypsum, clay, kaolin, limestone, diatomite and salt, further on.
10
HISTORICAL OVERVIEW OF MINING IN PORTUGAL
The mining of mineral resources in Portugal was initially carried out by the Phoenicians, but was in-tensely and mainly developed by the Romans.
The first mining operations would have taken place in “gossan” type oxidation zones (for copper, zinc, lead, gold and silver) and gold-bearing placers (Carvalho, 1994). The Romans would later intensely exploit gold and polymetallic sulphide vein depos-its. To better comprehend the size of the work in-volved, one need look no further than Três Minas, to the north of Vila Real, from which approximately 10 million tons of material was extracted; and in Aljustrel (southwest of Beja), mine shafts reached a depth of 120 metres.
Then followed a lengthy break in the mining of mineral resources in Portugal which was only oc-casionally interrupted, the exploitation of alluvial gold in Adiça near Lisbon during the XII century is one example of this.
From the middle of the last century, coinciding with the start of the industrial revolution, mining once more became an important industry in Portu-gal, with the first mining concessions being grant-ed in 1836.
By the end of the X1X century, approximately 300 concessions had been awarded, the main substanc-es exploited being polymetallic sulphides (Aljus-trel, S. Domingos), tungsten and tin (Panasqueira), and antimony and gold (Valongo/Gondomar).
At the start of the XX century, there was a marked increase in coal annual production.
The two world wars, particularly the Second World War, led to a great demand for tungsten, which in turn led to increased exploration and exploitation of not only this element but tin as well, as these two elements are generally related spatially and/or structurally. Production of the concentrates of these substances peaked during 1942 at 5700 tons for tungsten, the main producing mines being Pa-nasqueira, Borralha, Argozelo, Montesinho, Vale das Gatas and Ribeira.
The country also possesses important uranium de-posits, with approximately 4200 tons of U3O8 pro-duced between 1950 and 1990.
From the start of the fifties but mainly in the eight-ies, exploration underwent somewhat of a boom in Portugal, at first including tungsten and tin in the centre and north of the country and later concen-trating to precious metals and base metals, the lat-ter sought principally in the Pyrite Belt in the south, where a remarkable number of mineral masses have been discovered: Moinho (1955), Feitais (1963), Es-tação (1968), Gavião (1970), Salgadinho (1974), Ne-ves Corvo (1977) and Lagoa Salgada (1992).
The most important of these discoveries was the Neves Corvo deposit: since the mine came into op-eration, Portugal has become one of the most im-portant producers of copper (1988) and tin (1990) in Europe as well as tungsten from the last opera-tional mine (Panasqueira).
Portugal is also an important producer of ornamen-tal rocks, particularly marble, even at the interna-tional level.
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PROSPECTING AND EXPLORATION CONTRATS AND APPLICATIONS (27-12-2011)METALLIC MINERALS
12
LEGEND
CONTRACTS Nº Owner Minerals
441 MAEPA Cu, Pb, Zn, Au e Ag 965 MTI - FERRO DE MONCORVO Fe
1068 COLT RESOURCES INC Sb, As, Be, Bi, Pb, Co, Cu, Sn, Li, Mo, Nb, Ni, Au, Ag, Ta, W e Zn 1069 COLT RESOURCES INC Sb, As, Be, Bi, Pb, Co, Cu, Sn, Li, Mo, Nb, Ni, Au, Ag, Ta, W e Zn 1070 COLT RESOURCES INC Sb, As, Be, Bi, Pb, Co, Cu, Sn, Li, Mo, Nb, Ni, Au, Ag, Ta, W e Zn
12874 MAEPA Cu, Pb, Zn, Sn, Au e Ag 16871 COLT RESOURCES INC Au, Ag, Cu, Zn, Pb, Sb, W, Mo, Ta, Nb e Sn 38478 MTI - MINEIRA DE VINHAIS Sn e W 42082 IBERIAN RESOURCES PORTUGAL Au, Ag, Cu, Ni, Pb, Zn e minerais associados 42482 AM - ALMADA MINING Au, Ag, Cu, Pb, Zn, Sn, W, Li e Pirites 59689 MINAPORT Au, Ag, Pb, Zn, Cu, Sb, Sn e W 62491 MINAPORT Cu, Pb, Zn, Au e Ag 66496 MAEPA Cu, Pb, Zn, Au e Ag 90896 MAEPA Cu, Pb, Zn, Au e Ag 92098 IBERIAN RESOURCES PORTUGAL W, Sn, Au, Cu e minerais acessórios 92101 AGC Cu, Pb, Zn, Au, Ag, In e Sn 92102 REDCORP Cu, Pb, Zn, Au, Ag, Sn, Mn, Ba e Pirites 96497 SOMINCOR Cu, Zn, Pb, Sn, Ag, Au e Metais associados 96498 MAEPA W, Sn e Au 96896 NORTHERN LION GOLD Zn, Pb, Cu, Ag, Au, Sb, Ge, Ga e In 96897 NORTHERN LION GOLD Zn, Pb, Cu, Ag, Au, Sb, Ge, Ga e In 96898 NORTHERN LION GOLD Zn, Pb, Cu, Ag, Au, Sb, Ge, Ga e In
102096 CPF Fe e minerais associados 102097 EUROCOLT RESOURCES UNIPESSOAL Sb, As, Be, Bi, Pb, Cu, Sn, Li, Mo, Nb, Au, Ag, Ta, W e Zn 102098 EUROCOLT RESOURCES UNIPESSOAL Sb, As, Be, Bi, Pb, Cu, Sn, Li, Mo, Nb, Au, Ag, Ta, W e Zn 102099 EUROCOLT RESOURCES UNIPESSOAL Au, Ag, Cu, Pb, Zn e metais associados 102100 MAEPA Au, Ag, Cu, Pb e Zn 102101 MINAPORT Cu, Pb, Zn, Au e Ag. 102102 MINAPORT Cu, W, Sb, Au e Ag 102103 MINAPORT Cu, W, Sb, Au e Ag 102104 PANNN Li, Sn, Ta, Nb, W, Rb, Cu, Pb, Zn, Au, Ag e pirites 102105 PANNN Li, Sn, Ta, Nb, W, Rb, Cu, Pb, Zn, Au, Ag e pirites 109296 EDM Pt, Pd, Rh, Ru, Ir, Os, Re, Au, Ag, Ni, Co, Cu e Cr 109297 EDM Sn, W, Au, Ag, Cu e sulfuretos associados 109696 COLT RESOURCES INC Ba, Pb, Co, Cu, Sn, Fe, Mn, Ni, Au, Ag, Zn e pirites 109697 COLT RESOURCES INC Ba, Pb, Co, Cu, Sn, Fe, Mn, Ni, Au, Ag, Zn e pirites 109698 COLT RESOURCES INC. Sb, As, Be, Bi, Pb, Co, Cu, Sn, Li, Mo, Nb, Ni, Au, Ag, Ta, W e Zn 109699 COLT RESOURCES INC. Sb, As, Be, Bi, Pb, Co, Cu, Sn, Li, Mo, Nb, Ni, Au, Ag, Ta, W e Zn
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LEGEND
T , W e Zn
1 9 g
APPLICATIONS Nº Owner Minerals
251 IBERIAN RESOURCES PORTUGAL Au, Cu, U e minerais associados 448 BERALT TIN & WOLFRAM U, Th, Sn, W, Li, Ba, Cu, Pb, Zn, Au, Ag e P
40483 IBERIAN RESOURCES PORTUGAL Au, Ag, Cu, Pb, Zn, terras raras e minerais acessórios 50883 FRD - FERRO DOURO Fe 52483 MAEPA Cu, Pb, Zn, Au e Ag. 65691 MAEPA Au, Ag, W e Sn 76894 EDM Sn, W, Au, Ag, Cu e sulfuretos associados. 78494 MINERÁLIA W, Sn, Cu, Pb, Zn, Au e Ag 84496 REFERENCES & COORDINATES CONS. Sn, W, Cu, Zn, Ta, Ni, Ag e Au 86496 LUSORECURSOS ARG W, Sn, Au, Ag, Nb e Ta 96901 LUSORECURSOS ARG W, Sn, Au, Ag, Nb e Ta 96903 MAEPA Au, Ag e W 96904 MAEPA W, Pb, Zn, Cu, Au e Ag 96905 MAEPA Pb, Zn, Cu, Au e Ag 96910 MINERÁLIA Au, Ag, Pb, Zn e Cu 96911 LUSORECURSOS W e Sn 96916 SOJITZ BERALT TIN AND WOLFRAM Sn, W, Li, Cu, Pb, Zn, Au, Ag, e Pirites 96922 CPF Fe e minerais associados 96926 MAEPA Cu, Pb, Zn, Au, Ag, Ni, V, Mo e Sb 96927 MINERÁLIA Fe, Cu, Sb, Au e Ag 96928 MINERÁLIA Sn, W, Au e Ag 96944 MINERÁLIA W, Sn e Mo 96950 IBERIAN RESOURCES PORTUGAL W, Sn, Au e Cu 97296 MINAPORT Au e Ag 100896 MINERÁLIA W e Sn 101296 LUSORECURSOS TMG W, Sn, Au, Ag, Pb, Zn e Cu 101696 AM - ALMADA MINING Sb, Au, Ag, Cu, Pb, Zn, Sn, W e Pirites 106496 REDCORP Au, Ag, Cu, Pb e Zn 106896 LUSORECURSOS ARG W, Sn, Au, Ag, Ni e Ta. 107296 LUSORECURSOS ARG W, Sn, Au e Ag. 107696 EDM Au, Ag, Sn, W, Cu e sulfuretos associados 111296 MEDGOLD RESOURCES Minerais metálicos 111696 LUSORECURSOS ARG W, Sn, Au e Ag.
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PROSPECTING AND EXPLORATION CONTRATS AND APPLICATIONS (27-12-2011)NON METALLIC MINERALS
MINERAL RESOURCES
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CONTRACTS Nº Owner Minerals
927 SORGILA Caulino e Qz 12871 RODRIGUES & RODRIGUES Caulino 12873 GRALMINAS Qz e Feld. 13270 J. A. LAGOA & FILHOS Caulino 13271 J. A. LAGOA & FILHOS Caulino 13272 J. A. LAGOA & FILHOS Caulino 13273 J. A. LAGOA & FILHOS Caulino, Qz e Feld. 13274 SORGILA Caulino e Qz 26878 J. A. LAGOA & FILHOS Caulino 42084 FELMICA Feld, Qz e Li 66491 ARGILIS Caulino 66492 FELMICA Feld. e Qz 66493 FELMICA Qz e Feld. 66494 IMNP Caulino 66495 IMNP Caulino 66497 MOTAMINERAL Caulino e Qz 76494 GRALMINAS Qz 92099 CORBÁRIO Caulino e Qz 92100 CORBÁRIO Caulino e Qz
APPLICATIONS Nº Owner Minerals
181 FELMICA Qz e Feld 182 CAMPADOS Caulino 187 SORGILA Qz e Caulino 374 IMERYS CERAMICS PORTUGAL Qz, Feld. e Li 891 J. A. LAGOA & FILHOS Qz, Feld. e caulino 961 ADELINO DUARTE DA MOTA Caulino, Qz e Salgema
1002 ARGILIS Qz 1028 INERLENA Caulino e Qz 1258 REN Salgema 2460 SIFUCEL Qz e caulino 6868 INERLENA Qz e caulino 9669 J. A. LAGOA & FILHOS Qz, Feld e Li
15672 ADELINO DUARTE DA MOTA Caulino 16072 RODRIGUES & RODRIGUES Caulino 19271 ADELINO DUARTE DA MOTA Caulino 19671 FELMICA Qz 22872 SIBELCO PORTUGUESA Caulino e Qz 25674 J. A. LAGOA & FILHOS Qz, Feld e Li 25675 J. A. LAGOA & FILHOS Qz, Feld e Li 28476 SIFUCEL Caulino 30076 MINAS DE BARQUEIROS Caulino 32878 SORGILA Qz e caulino 37680 J. A. LAGOA & FILHOS Caulino e Qz 37681 J. A. LAGOA & FILHOS Caulino 39678 FELMICA Qz, Feld. e Li 39682 FELMICA Qz, Feld. e Li. 39683 FELMICA Qz, Feld. e Li. 43683 ZIDANIS Caulino e Qz 44882 J. A. LAGOA & FILHOS Qz, Feld e Li
16
64892 ALDEIA & IRMÃO Qz, Feld. e Li 64893 ALDEIA & IRMÃO Qz, Feld. e Li 72493 ALDEIA & IRMÃO Caulino 73293 GRALMINAS Qz 74093 ALDEIA & IRMÃO Qz, Feld. e Li. 79294 SOCASCA Caulino 79698 GRALMINAS Qz e Feld. 80097 ALDEIA & IRMÃO Feld. e Qz 83298 SORGILA Qz e caulino 84900 ZIDANIS Caulino, Salgema e Qz 85296 SILICALIA PORTUGAL Qz 95696 RUI M S MARTINS Qz e caulino 96908 J. A. LAGOA & FILHOS Caulino e Qz 96909 ALDEIA & IRMÃO Qz e Feld. 96912 SIBELCO PORTUGUESA Caulino e Qz 96913 ZIDANIS Qz e caulino 96915 FARIA LOPES & ALDEIA Caulino 96917 ALDEIA & IRMÃO Feld, Qz e Li. 96918 ALDEIA & IRMÃO Qz e Feld. 96919 J. A. LAGOA & FILHOS Caulino 96920 J. A. LAGOA & FILHOS Feld. e Qz 96921 FARIA LOPES & ALDEIA Qz e Feld. 96929 ALDEIA & IRMÃO Qz, Feld. e Li 96932 ALDEIA & IRMÃO Feld, Qz e Li. 96933 ALDEIA & IRMÃO Caulino 96935 ALDEIA & IRMÃO Caulino 96936 J. A. LAGOA & FILHOS Caulino 96941 MOTAMINERAL Caulino e Qz 96942 FELMICA Feld. 96945 SIFUCEL Feld. 96956 J. A. LAGOA & FILHOS Caulino 96957 LUSOSILICAS Qz e caulino 97302 SIFUCEL Caulino e Qz 97303 FELMICA Feld. e Qz 97305 CORBÁRIO Caulino 97306 CORBÁRIO Caulino 97307 CORBÁRIO Caulino 97308 J. A. LAGOA & FILHOS Qz, Feld. e Li 97309 MOTAMINERAL Caulino e Qz 97310 MOTAMINERAL Caulino e Qz 97311 MOTAMINERAL Caulino e Qz 97312 MOTAMINERAL Caulino e Qz 97313 MOTAMINERAL Caulino e Qz 97696 ALDEIA & IRMÃO Caulino
101698 SIFUCEL Qz e Feld. 101699 SIFUCEL Qz e Feld. 101700 LUSOSILICAS Qz, Feld. e caulino 102496 IMERYS CERAMICS PORTUGAL Feld e Qz
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731
104096 ZIDANIS Caulino, Salgema e Qz 104097 J. A. LAGOA & FILHOS Caulino 104896 ALDEIA & IRMÃO Caulino 106097 LUSOSILICAS Qz e caulino 108096 ALDEIA & IRMÃO Qz, Feld. e Li 108496 MOTAMINERAL Caulino e Qz 110496 ALDEIA & IRMÃO Qz e Feld. 110896 J. A. LAGOA & FILHOS Caulino 110898 UNIZEL Feld., Qz 96958 ALDEIA & IRMÃO Qz e Feld. 97299 SIFUCEL Qz e Feld. 97300 SIFUCEL Qz e Feld. 97301 SIFUCEL Caulino e Qz
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CONTRACTS Nº Owner Minerals 1 FELMICA Qz e Feld. 2 FELMICA Qz e Feld. 3 MIBAL Caulino 4 FELMICA Qz e Feld. 5 FELMICA Qz e Feld. 6 J. A. LAGOA & FILHOS Qz e Feld. 7 J. A. LAGOA & FILHOS Qz e Feld. 9 SOC. MINEIRA CAROLINOS Li e Sn
11 EDM S, Fe, Cu, Pb, Zn, Ag e Au 12 CUF Salgema 14 MOTAMINERAL Caulino 15 SOBAL Qz, Feld. e Be 16 UNIZEL Feld. e Qz 18 PEGMATÍTICA Caulino 19 MOTAMINERAL Caulino 20 GRALMINAS Qz e Feld. 21 QUARTEX Qz e Feld. 22 GRALMINAS Qz e Feld. 23 GRALMINAS Qz e Feld. 24 CAULINALVA Caulino 25 SOC. MINEIRA CAROLINOS Gl, Li, Sn, W, Ta, Qz e Feld. 26 SOC. MINEIRA CAROLINOS Qz 27 IMNP Caulino 28 MOTAMINERAL Caulino 29 IMNP Caulino 30 IMNP Caulino 31 SOMINCOR Cu, Zn, Pb, Au, Ag, Sn e Co 32 MINAS DA PEDRA MOURA Qz e Feld. 33 ROCÁVIA Qz e Feld. 34 COMITAL Talco 35 PORSTIN Sn e Ti 36 MOTAMINERAL Caulino 37 EMP. CERÂMICA DO FOJO Caulino 38 MCS Sn e Ti 39 MINAS DE CASSITERITE SOBREDA Sn e Ti 40 SIFUCEL Caulino 41 FELMICA Feld. e Qz 42 PEGMATÍTICA Feld. 43 FELMICA Feld. e Qz 44 PEGMATÍTICA Qz e Feld. 45 MITALCO Talco 46 MITALCO Talco 47 MITALCO Talco 48 MITALCO Talco 49 MITALCO Talco 50 FELMICA Sn, Feld. e Qz 53 SOLVAY PORTUGAL Salgema 54 SOLVAY PORTUGAL Salgema 55 A. J. DA FONSECA, LDA. Qz e Feld. 56 A. J. DA FONSECA, LDA. Qz e Feld. 57 JOÃO CERQUEIRA ANTUNES Qz e Feld.
7
20
LEGEND
50
58 JOÃO CERQUEIRA ANTUNES Qz e Feld. 59 CAULICENTRO Caulino 60 ENU U 61 EMP. MINEIRA DA SERRA DO CERCAL Au e Ag 63 J. A. LAGOA & FILHOS Qz e Feld. 64 MARCOLINOS Sn e W 65 COMP. S.PEDRO DA COVA Carvão 66 COMP. S.PEDRO DA COVA Carvão 67 FELMICA Qz e Feld. 68 COMITAL Ba 70 J. A. LAGOA & FILHOS Qz e Feld. 71 ENU U 72 ENU U 74 UNIZEL Feld. e Qz 75 EMP. MINEIRA DA SERRA DO CERCAL Fe e Mn 76 ENU U 78 CAMPADOS Caulino 79 FELMICA Qz e Feld. 80 FELMICA Qz e Feld. 83 SOC. MINEIRA DE FRANÇA Sn 84 SOC. MINEIRA DE FRANÇA Sn 85 SOPRED Sn 86 SOPRED Sn 87 SOPRED Sn 88 SOPRED Sn 89 A. J. DA FONSECA, LDA. Qz e Feld. 90 EMP. PORT.CAULINOS DE PARADA Caulino 91 FELMICA Qz e Feld. 92 FELMICA Qz e Feld. 93 FELMICA Qz e Feld. 99 J. A. LAGOA & FILHOS Qz e Feld.
101 ARGILIS Caulino 104 A. J. DA FONSECA, LDA. Qz e Feld. 105 J. A. LAGOA & FILHOS Qz e Feld. 108 RENOESTE Salgema 114 J. A. LAGOA & FILHOS Qz e Feld. 121 ALDEIA & IRMÃO, S.A. Feld. e Qz 128 IMERYS CERAMICS PORTUGAL Feld. e Qz 129 BERALT TIN & WOLFRAM W, Sn, Cu, Ag, Zn e As 131 PIRITES ALENTEJANAS S, Cu, Zn, Pb e Ag 134 FELMICA Qz e Feld. 135 FELMICA Qz e Feld. 181 MINAS DE BARQUEIROS Caulino 594 FELMICA Feld. e Qz 595 IMERYS CERAMICS PORTUGAL Caulino 596 UNIZEL Feld. e Qz 597 FELMICA Feld., Qz e Li 598 J. A. LAGOA & FILHOS Caulino 638 FELMICA Feld., Qz e Li 639 ARGILIS Caulino 640 GRALMINAS Gl, Feld. e Qz
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LEGEND
95 5
640 GRALMINAS Gl, Feld. e Qz 643 ADELINO DUARTE DA MOTA Caulino e Qz 644 ADELINO DUARTE DA MOTA Caulino e Qz 647 ALDEIA & IRMÃO, S.A. Caulino 648 SIFUCEL Qz e caulino 649 J. A. LAGOA & FILHOS Feld. e Qz 992 MOTAMINERAL Caulino e Qz
1395 (ESTADO) Sn, Ta, Qz e Feld. 15407 SIBELCO PORTUGUESA Caulino e Qz 15408 SIFUCEL Caulino e Qz 15409 ADELINO DUARTE DA MOTA Caulino e Qz 15807 ADELINO DUARTE DA MOTA Caulino e Qz 15808 ADELINO DUARTE DA MOTA Caulino e Qz 15809 FELMICA Feld., Qz, Li e Ta 15810 FELMICA Feld. e Qz 15811 FELMICA Feld., Qz e Li 15812 GRALMINAS Qz 15813 LUSOSILICAS Caulino e Feld. 15814 SILICÁLIA PORTUGAL Qz 15815 SILICÁLIA PORTUGAL Qz 22607 J. A. LAGOA & FILHOS Caulino 24607 IBERIAN RESOURCES/COLT RESOURCES INC. Au, Ag, Cu, Pb, Zn e minerais associados
250 7
22
LEGEND
APPLICATIONS Nº Owner Minerals 69 FRANCO, LDA. Qz e Caulino 95 ARGILIS Qz, Feld. e Caulino 96 FELMICA Qz e Feld. 98 FELMICA Qz e Feld. 100 J. A. LAGOA & FILHOS Qz, Feld. e Caulino 109 CAMPADOS Caulino 111 ADELINO DUARTE DA MOTA Caulino 115 MCS Sn e Ti 116 ARGILIS Caulino 118 SOC.AGRÍC. GOUXA E ATELA Turfa 123 ALDEIA & IRMÃO, S.A. Qz e Feld. 130 J. A. LAGOA & FILHOS Qz e Feld. 144 ADELINO DUARTE DA MOTA Caulino 157 J. A. LAGOA & FILHOS Qz e Feld. 160 FELMICA Qz e Feld. 166 LAGOASOL Caulino 172 ADELINO DUARTE DA MOTA Caulino 173 ADELINO DUARTE DA MOTA Caulino 174 ADELINO DUARTE DA MOTA Caulino 180 SILICÁLIA PORTUGAL Qz 182 ADELINO DUARTE DA MOTA Caulino 591 ADELINO DUARTE DA MOTA Caulino 603 ARGILIS Caulino 607 CAULIAREIAS Caulino 612 FELMICA Qz, Feld. e Li 617 UNIZEL Feld. e Qz 618 LAGOASOL Caulino 619 LAGOASOL Caulino 623 SORGILA Caulino 626 ALCOAREIA Caulino 627 SORGILA Caulino 629 FELMICA Qz, Feld e Li 633 MOTAMINERAL Caulino, Feld e Qz. 637 CAULIAREIAS Caulino 651 FELMICA Feld., Qz e Li 652 FELMICA Feld., Qz e Li 656 FELMICA Feld., Qz e Li
1795 SORGILA Caulino 1796 SORGILA Caulino 1797 FELMICA Feld. e Qz 1798 FELMICA Feld. e Qz 2199 ARGILIS Caulino 3401 FELMICA Qz, Feld e Li 3802 SULAREIAS Qz 4203 SORGILA Caulino 5005 CUF Salgema 5405 MINAS DE CASSITERITE SOBREDA Sn e Ti 5805 SOC. MINEIRA CAROLINOS Li e Sn 6605 FELMICA Qz e Feld. 7005 GRALMINAS Qz e Feld. 9405 SALCAVE Salgema
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LEGEND
5005
9406 SARBLOCO Qz e caulino 10606 J. A. LAGOA & FILHOS Qz e caulino 11406 SORGILA Caulino 11806 J. A. LAGOA & FILHOS Caulino 11807 MTI - FERRO DE MONCORVO Fe 12207 IMERYS CERAMICS PORTUGAL Feld., Qz e Li 13407 J. A. LAGOA & FILHOS Qz e Feld. 13807 UNIZEL Qz, Feld. e Li 16208 A.M. - ALMADA MINING Au e Ag 16607 EDM Au, Ag, Cu, Pb, Zn e min. associados 17407 SOPRED Feld. e Qz 17807 MTI - MINEIRA DE VINHAIS Sn e W 18207 FELMICA Qz e Feld. 18607 IBERMIN Au, Ag, Cu, Pb, Zn e min. associados 19007 FELMICA Feld., Qz e Li. 19008 FELMICA Feld., Qz e Li. 19407 AM - ALMADA MINING Au, Ag, Cu, Pb, Zn e minerais associados 19408 REDCORP Au, Ag, Pb, Zn e Cu 19409 J. A. LAGOA & FILHOS Qz e Feld. 19807 FELMICA Feld. e Qz 20207 SORGILA Caulino e Qz. 20607 SORGILA Caulino e Qz. 21007 J. A. LAGOA & FILHOS Caulino 21407 J. A. LAGOA & FILHOS Caulino e Qz. 21408 J. A. LAGOA & FILHOS Caulino e Qz. 21409 J. A. LAGOA & FILHOS Caulino 21410 J. A. LAGOA & FILHOS Caulino 21807 RODRIGUES & RODRIGUES Caulino 23007 CORBÁRIO Caulino 23008 CORBÁRIO Caulino 24207 CORBÁRIO Caulino 25007 J. A. LAGOA & FILHOS Qz e Feld. 25407 EDM S, Fe, Cu, Pb, Zn, Ag e Au
24
INVESTMENTS IN EXPLORATION (2001-2010)
Mineral Production in 2007 (1000 euros) Mineral Production in 2010 (1000 euros)
Construction minerals; 518.121
Construction minerals; 521.140
Metalic minerals; 484.603
Metalic minerals; 427.604
Industial Minerals; 22.587
Industial Minerals; 50.978
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ARIÇA/EDROSA - Auriferous mineralisation oc-curs associated with sulphides (arsenopyrite, pyrite, sphalerite, galena and chalcopyrite) and embedded in a Silurian volcanic sedimentary complex, clearly controlled by the Hercynian orogeny (Knopf et al., 1990), which causes an alignment of the mineralised structures (quartz and porphyry veins) in a NNW-SSE direction.
POÇO DAS FREITAS/LIMARINHO -The mines in this area date back to Roman times and have left behind a series of small open pits, the largest of which is roughly 100 metres long and 80 metres in width. Mineralisation, which is associated with stockworks of quartz veins, occurs embedded in granitic rocks, running parallel to the large Ré-gua/Verin fault and corresponding to a possible shear zone.
In Limarinho the existence of possible reserves of 2.07 tons of gold with an average grade of 2.8 g/t was pointed out.
TRÊS MINAS - This was the largest Roman mine in Portugal, and consists of three open pits running WNW-ESE, two of which are of an impressive size (Ribeirinha and Covas), the largest approximately 500m long, 100m wide and 80m to 100m deep. There are also numerous shafts and galleries (the largest of which is 250 metres in length with a 5 x 1.5m cross-section). It is estimated that 10 mil-lions tons of material have been mined here.
As in the NW of Spain, the Romans employed the “ruina montium” mining technique, which was usual practice for low grade, high tonnage deposits. Gold occurs associated with arsenopyrite and pyrite, in quartzite lenses interstratified with Silurian shales,
and appears to be of syngenetic (paleoplacers) and epigenetic (tectonic control) origin.
JALES/GRALHEIRA - The first mining operations carried out in this zone also date back to Roman times, and has become this century the largest gold mine in Portugal. Hydrothermal gold-bear-ing quartz veins occur here in two main direc-tions (NE-SW and WSW-ENE), coincident with sub-vertical fractures embedded in Hercynian granites and schists, greywackes and quartzites from the Schist-Greywacke Complex, and mainly from the Silurian age. These lodes are sometimes as long as 2.5 kms and although their thickness varies, they never exceed 1 metre width. The two main lodes, which run in a NE-SW direction, are known as Campo and Desvio. Gold and electrum occur associated with quartz and sulphides (ar-senopyrite, most common, pyrite, pyrrhotite, chalcopyrite, sphalerite, tetrahedrite, galena). Grade is fairly irregular, although figures of 30-40 g/t Au were frequently found. Since 1933, the mine has produced approximately 25 tons of gold and 100 tons of silver; at the time of its closure in 1992, it had reached a depth of 620 m. Recently was determined that the Campo lode continues approximately 600 m south of the old mining works, in a structure known as the Horta vein, although mineral grade is highly variable. In the Gralheira structure - a shear zone with several veins, running in a WSW-ENE direction, embed-ded exclusively within metasedimentary Silurian rocks and located NE of the Campo and Desvio lodes - the existence of a mineralised zone that extends for at least 1850 metres and is roughly 15 metres thick was determined. Recently, meas-ured and indicated resources of 363 000 tones, with a grade of 6,47 g/t of gold (2346,7 kg) and
Galicia - Trás-os-Montes Zone
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27,12 g/t of silver (9482 kg), with a cut off of 4 g/t, were defined for this area.
LATADAS/FREIXEDA/PEDRA DA LUZ - Minerali-sation occurs in quartz veins embedded in the Trás-os-Montes volcanic-siliceous and quartz-phyllite Silurian complexes, which are occasion-ally intruded by alkali granites. The veins that run predominantly in a NE-SW and E-W direction, in a shear zone, were also worked by the Romans. The gold is mostly associated with W, As, Cu, Pb, Zn and Sb polymetallic sulphides. Recently, a drill-ing campaign developed on the Pedra Luz sector show the existence of a sulphides level, embed-ded on acid volcanic rocks, with high grades of precious, base and other metals: 2,13 % W in 4,75 m, including 0,35 m with 15,88 g/t Au, 296 g/t Ag, 1,45 % Cu, 1,22 % Pb and 4,65 % Zn.
VILA VERDE/PONTE DA BARCA - Prospecting car-ried out at the end of the eighties uncovered a NE-SW alignment that had gold-bearing poten-tial, the following areas being the most impor-tant:
Marrancos - mineralisation is related with a shear zone which affects the Silurian metasediments, these transformed into hornfels by contact meta-morphism. In the zone affected by this shearing, breccias and silicifications are to be found accompa-nied by sulphide mineralisations (arsenopyrite and pyrite) with gold.
Godinhaços - mineralised structures (gold + arseno-pyrite) are located exclusively in the granite of Vila Verde. There appears to be lithological control of the mineralisation, the veins running predominantly in an NE-SW direction.
Grovelas - characterised by the occurrence of a dense network of joints filled with arsenopyrite and running predominantly N 25º - 40º E and N 50º - 70º E. There appear to be two mineralised axes, the in-tersection of which could prove to be an enrichment zone. Also worthy of mention is the existence of old Roman mining works.
Central – Iberian Zone
VALONGO/GONDOMAR - This gold-antimony belt is situated in Baixo Douro region, north-east of Oporto and stretches from Esposende to Castro Daire in a distance of 90km. Besides Sb-Au occurrences exist also Au-As, Pb-Zn (Ag) and Sn-W mineralisations, which are located in the large Valongo anticline and in the Carbon-iferous syncline, embedded in metasedimen-
tary formations dated from Precambrian and/or Cambrian to Carboniferous and more rarely in hercynian granites.
In remote times, initially the Phoenicians, later and chiefly the Romans, exploited gold in this mining district. At the end of the XIX century, this belt was extensively mined for antimony; and, as a sub-prod-
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uct, gold contained in quartz veins. We can remark the production from the ancient mines of Ribeiro da lgreja (Sb-Au), Montalto (Sb-Au) and Banjas (Au-As) not forgetting the silver Terramonte mine that during the sixties was one of the most important in Europe. Lead and zinc were also mined here.
Studies undertaken by several operators, indicated the occurrence of gold-antimony mineralisations of stockwork type in Alto do Sobrido and of saddle reefs type in Banjas. More recent works show that gold is not restricted to the quartz veins but per-vades, within shear zones, the pores and fractures of their host rock; in consequence of this discovery quartz stockworks and silicified mineralised bodies with gold and antimony were found in Alto do So-brido and these orebodies illustrate the excellent mineral potential of the area. In Alto Sobrido, the definition of 1 069 354 tones with a grade of 1,07 % of Sb, is worth mentioned.
CASTROMIL - This area, which was first mined in Roman times, is located within a Hercynian granite near its contact with Silurian metasedi-ments, part of the Eastern flank of the Valongo anticline. The latter is characterised by the oc-currence of various gold/antimony deposits, as mentioned earlier. Two important orthogonal fault systems occur in this zone: NW-SE and NE-SW. The latter, which is more recent, is of great metallogenetic importance and appears to represent the hydrothermal conduits. Gold is essentially disseminated along veins in the silicified granite, running NW-SE, related with a shear zone and frequently associated with sulphides (arsenopyrite and principally pyrite). Besides the silicification, other alteration phe-nomena, such as sericitisation and kaolinisa-
tion, also play an important role. In paragenetic terms, three stages of mineralisation are consid-ered: ferro-arseniferous (quartz + arsenopyrite I + pyrite I + pyrrhotite + bismuth?), zinciferous (sphalerite + chalcopyrite), and remobilisation (arsenopyrite II + galena + gold).
Two fields were defined: Covas de Castromil and Serra da Quinta, separated by the Sousa river and the Oporto-Pocinho railway. For the first of these fields, proved reserves of 2,147,000 tons have been determined with an average grade of 1.9 g/t Au (cut-off of 0.5 g/t) and probable reserves of 270,000 tons with 1.8 g/t Au. For Serra da Quinta, probable reserves are put at 743,000 tons with 2.8 g/t Au.
PENEDONO - In this area, also worked by the Ro-mans, various gold-bearing quartz veins occur. These are sub-vertical and run predominantly in a NE-SW direction. Gold is chiefly to be found in the arsenopyrite and it does appear that val-ues are not disseminated between veins which are not spaced closely enough to allow for open pit mining. However it also occurs in heavily sericitised fractures within the Hercynian gran-ite near the contact with the Cambrian meta-sediments of the Schist-Greywacke Complex. Around 50 years ago, this area produced gold (Stº. António mines) with an average grade of 14 g/t. Prospecting studies are currently being carried out on Santo António–Vieiros, Paredes–Dacotim and Turgueira sectors, where a poten-tial geological resource of more than 500.000 ounces of gold is delineated.
CARAMULO - Another area worked by the Ro-mans where gold occurs associated with pyrite and arsenopyrite in quartz lenses. There is a
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tectonic control, suggesting the existence of a NNW-SSE shear zone, parallel and related to the Oporto-Tomar thrust system with a maximum width of 500 metres and a length of several kilometres. Taking both this and the geochemi-cal mapping of gold obtained from soil samples into account, it is likely that mineralisation also occurs in the schist -greywacke wall rocks.
ESCÁDIA GRANDE - At this old mine, that was also worked by the Romans, there was gold production during the forties. Mineralisation occurs associated with quartz vein structures running NW-SE, dipping SW, probably related with the Oporto-Tomar thrust system, and con-sists of polymetallic sulphides (pyrite, arseno-pyrite, sphalerite, galena and chalcopyrite) in which the gold is finely disseminated. The wall rock belongs to the Schist-Greywacke Complex and is frequently altered by silicification and carbonisation phenomena, with which the min-eralisation is associated. PORTALEGRE - This area is located within the Tomar-Badajoz Blastomylonitic Belt. Gold oc-curs predominantly associated with silicified, chloritised and carbonated metavolcanic sedi-mentary levels of the Precambrian Série Ne-gra in the Mosteiros and S. Martinho (Alter do
Chão) sectors. In the latter, the existence of Plio-Pleistocene covering deposits (gravel) bearing secondary gold mineralisation is also worthy of mention. Drilling executed in the S. Martinho sector have provided extremely positive results (2m with 49 g/t Au, 4m with 12.7 g/t Au and 33.43m with 1.2 g/t Au).
The gold is usually accompanied by pyrite, pyrrho-tite and arsenopyrite.
MONTEMOR-O-NOVO -Gold-mineralisations are concentrated in tabular zones, normally charac-terised by heavy silicification and embedded in a Precambrian volcanic sedimentary sequence along a belt over 30 kilometres in length. Re-search undertaken has determined the exist-ence of various deposits with marked lithologi-cal and tectonic control, the most important of which are located in the SE sector of the area: Banhos, Casas Novas, Chaminé, Ligeiro, Caras, Covas and Braços. Some free gold occurs, but normally it is associated with grains of arseno-pyrite and loellingite.
Recently, indicated resources of 1,23 Mt were de-fined for the Casas Novas, Chaminé and Braços de-posits, with a grade of 4,45 g/t Au and a cut off of 1,5 gt/ Au.
South – Portuguese Zone
CAVEIRA, ALJUSTREL and S. DOMINGOS - Gold has been mined here since Roman times in gos-san zones of polymetallic sulphide deposits, em-
bedded in a volcanic sedimentary complex dat-ing from the Late Devonian - Early Carboniferous period.
30
Despite the fact that they have been intensely ex-ploited in Roman times, they are not properly stud-ied.
The most important are the deposits of Alva (Ar-ganil), Arouce (Ceira River), Monfortinho (Erges River), Penamacor (Águeda River), Milreu and Mar-tinchel (Zézere River), Rosmaninhal and Constãncia-Abrantes (Tagus River). The volume of sand and gravel extracted from these sites has been calcu-lated at several million cubic metres. Some of them also contain channels that have been hewn in the bedrock to help concentrate the gold.
Based on the above considerations and the metal-logenetic characteristics of the country, we can de-fine the following areas as being potentially rich in precious metals: Vila Verde/Germil(2), Valongo/Gon-domar(6), the Blastomylonitic Belt (1), the Alentejo GoldArsenic -Antimony Belt(13) (Au,Ag), Caminha/Braga(l), Gerês/Mogadouro(3), Ervedosa/Argozelo (4), the Douro Scheelitic Belt (5), the Paiva Tungs-tiniferous Belt(7) , Arouca/S. Pedro do Sul(8), Tranco-so/Figueira de Castelo Rodrigo(9), Gois-Segura(10) (W, Sn, An), Sousel/Barrancos(12), Magnetitic-Zincif-erous Belt(14) and Porphyries of Beja(15) (Zn, Cu, Pb, Ag, An).
We feel that in the future special attention should be given to three metallogenetic scenarios (Viegas et al., 1992):
a) The mineral deposits occurring in the Blastomylo-nitic Belt(11) or its dependent areas, characterised by b tectonic control, frequently in shear zones as equally happens in the Galicia-Trás-os-Montes and Central-Iberian Zones, related with the Régua-Verin and Vilariça faults.
b) Gold-bearing mineral deposits associated with granitic intrusions and occurring within it or in the contact with the wall rock (especially skarns) and as a result potentially existing in belts also favourable to W and Sn mineralisations, probably in geochemi-cal spatial relationship with these elements (1, 3, 4, 5, 7, 8, 9, 10).
c) Mineralisations occurring in the surrounding for-mations (Silurian volcanic sedimentary complex) of the Morais and Bragança massifs, characterised by their association with polymetallic sulphides and/or shear zones.
Secondary Deposits
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mations. Occurrences of Cu, Pb and Zn are mainly related with intermediate-acid Cambrian metavol-canics, sometimes with associated agglomerated tuffs. Small occurrences of Pb-Zn are also known to exist in the Early Cambrian carbonated formation, particularly where this is more fractured and silici-fied.
IC - SOUSEL - BARRANCOS BELT
This basically corresponds to Cambrian, Ordovi-cian, Silurian and Devonian formations.
There are essentially three types of mineralised structure here: vein, stratiform and disseminated types.
In the first, which basically consists of copper min-eralisations, there exist subconcordant veins and veins that are completely discordant from the for-mations in which they are embedded. The most important of the sub-concordant veins are perhaps Miguel Vacas and Mociços ore-bodies, situated at the base of the Silurian, and Urmos, located in basic metavolcanics (spilites) from the Mid Cambrian.
The most important of the discordant veins are Minancos, from the base of the Silurian, Bugalho Mine, in Silurian formations not far from its base and near the Messejana fault, and Zarnbujeira, in Ordovician formations. The Mostardeira, Aparis and Botefa veins are also discordant, and all are situat-ed on the SW flank of the Terena syncline, which is essentially made up of flysch formations from the Devonian period.
With regard to stratiform mineralised structures, these are closely related to a Cambrian-Ordovician
I - NORTH ALENTEJO AREA
Given the nature, typology and regional geological setting of the mineral occurrences, this area is split into three belts:
Arronches – Campo Maior Belt
Alter do Chão – Elvas Belt
Sousel – Barrancos Belt
IA – ARRONCHES – CAMPO MAIOR BELT
This belt basically consists of Late Precambrian for-mations belonging to the Tomar -Badajoz Blasto-mylonitic Belt.
Occurrences of copper and, more rarely, lead are represented by the old Tinoca, Azeiteiros and Balô-co mines. Stratiform mineral occurrences, with dis-seminated sulphides, are located near the contact between different types of gneiss and associated with a felsic volcaniclastic formation.
The existence of high metamorphic gradients, related with important tectonic accidents and consequent hydrothermal activity, resulting in si-licification, chloritization and muscovitization phe-nomena, appears to have significantly contributed to the concentration of mineralisations of pyrite, chalcopyrite, pyrrhotite, magnetite and, more rare-ly, argentiferous galena.
IB – ALTER DO CHÃO – ELVAS BELT
This belt essentially corresponds to Cambrian for-
34
discordance. Mineralisations basically include py-rite, sometimes massive and rare chalcopyrite, sphalerite and galena. Mineralisations of pyrite, sphalerite and galena also occur in dolomitic lime-stones from the Early Cambrian, in microfractures and particularly in brecciated facies.
The disseminated mineralisations formed essen-tially of pyrite and chalcopyrite are associated with post-Silurian, intermediate-acid, sub-volcanic structures and constitute the cement of eruptive breccias. Mineralisation is more intense when the elements of these breccias are predominantly of a carbonated nature.
II - ÉVORA - BEJA MASSIFS
In view of the nature, typology and regional geo-logical setting of the mineral occurrences, 3 belts have been defined in these massifs:
Arraiolos – St. Aleixo Belt
Magnetitic – Zinciferous Belt
Porphyry Belt
IIA – ARRAIOLOS – STº. ALEIXO BELT
Various occurrences of copper, mainly of vein type, are known to exist here, some of which have been exploited on a small scale (Azaruja, Monte do Trigo, Reguengos and S. Aleixo). These mineralisations are related with both granodiorite intrusions and basic volcanics commonly spilitized.
IIB - MAGNETITIC - ZINCIFEROUS BELT
This basically comprises Cambrian, Ordovician and Silurian formations, intruded by several Hercynian granitic massifs such as Pias and Pedrogão.
The most important deposits in this belt are Al-gares (Cu, Pb, Zn) and Balsa (Pb, Zn) in the Portel region, Enfermarias (Zn, Cu, Pb) and Preguiça (Zn, Pb), in Moura and Sobral da Adiça regions respec-tively, and other occurrences of Pb, Sb, Ag, Zn in the Ficalho-Moura-Vale de Vargo triangle.
The Balsa and Preguiça deposits are associated with dolomitic limestone; those at Algares and Enfermarias are related with an intermediate-acid volcanic episode which occurred at the base of the Early Cambrian, contemporaneous with a carbon-ated sedimentation, with which an important hy-drothermal system is associated.
The Enfermarias “hidden deposit”, located essen-tially by gravimetry and confirmed by drilling, il-lustrates nicely base metal prospecting in the Mag-netitic - Zinciferous Belt. Deposits of Zn and Pb are also represented in paleokarsts, which contain very high levels of these elements, an example of which is the old Vila Ruiva mine.
The geological resources estimated for the Preguiça deposit on the sixties were of 1 million tones with 8% Zn and 2% Pb. More recently, 4,6 million tones with an average grade of 0,8% Pb were defined for the Enfermarias deposit.
Taking into account that both deposits are open in depth and there is a lot of other lead and zinc geo-
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volcanic rocks - namely rhyodacites, felsites, spi-lites and basalts - predominate and which are sur-rounded to the NE and SW by diorites, gabbros and ultrabasic rocks. The most significant mineral oc-currences are Corte Pereiro, Caeirinha, Alcáçovas, Peroguarda and Asseiceiras.
chemical anomalies and occurrences, we can say that in this area we may have potential geological resources of 10 million tones with about 10% of Pb and Zn combined.
IIC - PORPHYRY BELT
This covers a wide area in which sub-volcanic and
South-Portuguese Zone
This zone is characterised by the Iberian Pyrite Belt (IPB), which is known around the world for its large deposits of massive polymetallic sulphides and plays an important role in supplying Europe with base metals.
Up until the eighties, the prospecting of massive polymetallic sulphide deposits was mainly carried out in areas where formations of the Volcanic Sedi-mentary Complex (VS), potential bearers of sul-phide masses, outcropped or were expected to lay at depths not significantly exceeding 300 metres (Oliveira et al., 1998).
These areas were thoroughly prospected dur-ing the sixties, during which there was a marked turnaround in the methodology that had hitherto been used as a result of the evolution in the geo-logical models related with the formation of these deposits and the introduction of new prospecting techniques and systematic gravimetric coverage, which in turn brought about great improvements in discovering mineral deposits. The changes in both corporate sector and in official departments led to important discoveries being made, most of
them situated near mining centres or known occur-rences, as referred above.
The Pyrite Belt has been of great interest to private companies in the mining sector for many years, this clearly reflected in the number of prospecting con-tracts that have been signed with the Portuguese State.
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These facts, coupled with the scientific and tech-nological breakthroughs that took place during the eighties (in respect of both the geology and metal-logeny of the IPB, and the geophysical techniques applied - advances in high sensitivity airborne magnetometry and time domain electromagnet-ics, as well as data processing), meant that pros-pecting in this metallogenetic province moved into areas where the VS ocurred at great depths bellow the flysch sediments and/or the Tertiary. ln recent years this trend continued, the number of compa-nies prospecting in such areas has risen as techno-logical advances and computer data processing have boosted their ability to detect mineral masses at hitherto unreachable depths and/or in particu-lar adverse geological contexts such as conductive overburden.
Targets that might prove of interest in those areas are mostly located at great depth, where potential mineral-bearing horizons occur under a thick cov-ering of flysch or beneath nappes, the thickness of which is often uncertain. The depth of drilling here reach levels that were unthinkable several years ago, these usually around the 600 m and 1000 m mark, occasionally going even further.
Despite those developments, the basic tools used since the sixties - gravimetry combined with spe-cialized geological mapping and magnetometry (with ground vertical component surveys replaced by high-resolution total field airborne surveys and ground follow-up work) - still play a major role.
Other complementary geophysical techniques are also routinely used, mostly in previously detect-ed gravimetric anomalies. Those include vertical electrical soundings, classic and high-resolution
(SQUID-TEM) electromagnetic soundings and bore-hole logging, and other electrical techniques such as induced polarization and magnetotelurics. In a limited fashion, reflection seismics has also been used. Another geochemical technique that has been used is the enzyme leaching of soil samples.
Although a few localized helicopter surveys, name-ly aeromagnetic and EM (INPUT and frequency domain) had been done in the eighties, a regional airborne high resolution magnetic and 256 chan-nel spectrometric geophysical survey has been developed. Those coverages have greatly contrib-uted towards better geological mapping, defining regional geological structures, tectonic accidents, buried volcanic axes, and conductors, providing in-formation that might indicate the presence of min-eral masses deep bellow the surface.
We now move on to the most important mineral deposits and mines in this metallogenetic province (Fig. 6), from NW to SE although other deposits do exist (Caveira, Montinho, Chança, Salgadinho and Cercal, the last currently being mined for Fe and Mn):
LAGOA SALGADA - In this area, located in the Ter-tiary Basin of the Sado River but included in the NW segment of the IPB, varied exploration work was carried out which, thanks mainly to gravimetry, has uncovered several targets. In one of them, situated roughly 12 km NE of Grândola, a mass of polym-etallic sulphides was discovered in August 1992 at a depth of 128 metres under tertiary covering.
Boreholes executed in the central and NW nuclei oft he gravimetric anomaly of Lagoa Salgada have revealed a pyrite-bearing acid volcanic sequence accompanied by polymetallic sulphides, the NW
38
nucleus the richer of the two (Oliveira et al., 1998). Here, the mineral mass is embedded in a volcanic sequence highly altered by an important hydro-thermal system. The main volcanic facies are com-posed of intermediate - acid lavas and autoclastic breccias with abundant feldspar megacrystals, and fine, sometimes porphyrous, chloritic-sericitic volcanics; intercalated layers of possible lapilli are frequent. Note that the enormous tectonic com-plexity that affects the mineralisation and wall rock makes investigation of the zone extremely difficult.
There are four types of mineralization at Lagoa Salgada: primary massive sulphide mineralization, gossan mineralization resulting from weathering of the primary mineralization, copper-rich stock-work mineralization and gold-rich silicified zones which appear to be structurally controlled. To date the mineralized system has been drill tested over a strike extent of approximately 425 m and appears to be open to the south and east.
The massive sulphide mineralization occurs in steeply dipping to vertical isoclinally folded vol-canic rocks. The mineralised mass begins with an iron hat of variable thickness - never greater than 20m -where
there is marked enrichment of precious metals, Sn and some times Pb, preserved as a result of the Ter-tiary sedimentary rocks covering the paleosurface, in a situation analogous to the Las Cruces copper deposit in Spain. This enrichment in Au and Ag is also visible in the first section of the mass, immedi-ately underlying, due to supergenic phenomena, or next to important thrusts and consequent remobi-lizations. The gossan has the following paragenesis: goethite, hematite, amalgams of Ag - Hg, chalcoc-ite, neodigenite, covellite, bornite and mimetite. The primary mineralisation is composed mainly of pyrite with the following minerals: sphalerite, arse-nopyrite, tetrahedrite, tennantite, galena, lollingite, chalcopyrite, cassiterite, stannite, meneghinite and pyrrhotite.
Copper-rich stockwork mineralization consists of sulphide veins and stringers in chloritic volcanic rocks and represents alteration associated with the feeder system to the massive sulphide mineraliza-tion.
The mineral resource estimate for the deposit (De-cember 2011), at 3.5 ZnEQ% cut-off, is as indicated in the following tables:
INDICATED RESOURCE
ZnEQ%Cutt-off
Density Tonnes(x 000t)
Pb% Zn% Cu% Ag (g/t) Au (g/t) ZnEQ%
3.50% 4.43 2,942 2.94 3.40 0.34 54.72 0.82 7.18
MINERAL RESOURCES
OF PORTUGAL
39
the outcropping masses of S. João and Algares. An important archaeological find was made here: two bronze tables inscribed with the mining law of those times.
In this area, the VS occupies the axis of an anticlino-rium running in a NW-SE direction and is charac-terised by the existence of an important sequence of acid pyroclastic rocks, subdivided into lower and upper series(Silva et al., 1997). These rocks are in turn subdivided into two laterally equivalent se-ries. In the central part of the structure there is a sequence which includes the lower unit with tuffs with megacrystals, and the upper with green tuffs; laterally, the lower series is characterised by the ex-istence of volcanics with felsic facies; and the up-per, known as the tuffs of the mine formation, is the bearer of masses of massive polymetallic sulphides.
The Messeiana fault has a sinistral displacement of roughly 2.5 km, causing locally a change in the di-rection of the structures from NW-SE to E-W Later it caused the NW block to lower and be covered by tertiary sediments. Thus, the sector of the Gavião deposit, which constitutes the extension of the Aljustrel structure, presents a tertiary cover of 60 - 90m.
LOUSAL - Old mine situated on the SW flank (in-verse) of the Lousal anticline. Mineralisation is found in a deep, narrow syncline, characteristic of the VS occurring here, which is deeply folded with-in isoclinal structures. Several masses have been recognised with tonnages of 100,000 tons to over 3MT, essentially pyrite, generally lenticular, aligned along the axis of the folds, dipping roughly 80º to the SW and extending several hundred metres with variable thickness.
The ore is relatively poor in Cu (<0.7%) and in Pb + Zn (1.1 - 3.5%), with annual production at the start of the seventies totalling between 230,000 and 250,000 tons. The mine was closed down in 1987.
Recently, two drill holes has intersected: 10.65m @ 0.84% Cu (656.35-667.00m) and 7.85m @ 1.45% Zn (832.15-840.00m) in the first one and 28 m @ 0.92% Cu and 80.2 ppm Ag (615.00-643.00m) and 8.50 m @ 2.97% Zn, 1.12% Pb and 46.9 ppm Ag (687.10-695.60m) on the second one. Some interesting grades were also found for precious metals, maxi-mum of 13.35g/t Au e 120g/t Ag.
ALJUSTREL - Mining at this important mineral de-posit dates back to Roman times, the target being
INFERRED RESOURCE
ZnEQ%Cutt-off
Density Tonnes(x 000t)
Pb% Zn% Cu% Ag (g/t) Au (g/t) ZnEQ%
3.50% 4.04 1,554 2.50 1.80 0.35 51.00 0.78 5.54
40
The following masses have been recognised: Al-gares, S. João, Moinho, Feitais, Estação and Gavião, all occurring in well defined structural positions in the Aljustrel Anticlinorium, running parallel and symmetrical to the alignments of the felsic facies, mine tuffs which are: the S. João Syncline, contain-ing the deposits of S. João, Moinho, Algares and the NE Gavião mass; a second alignment symmetrical to the latter includes the SW Gavião mass; finally, the Feitais and Estação deposits are located on the NE flank of the referred anticlinorium.
S. João and Algares were exploited up until the mid-sixties, the latter now exhausted, Moinho and
Feitais were mined in more recent decades, while mining operations have never taken place at Es-tação and Gavião.
Various types of ore can be distinguished in the Moinho and Feitais deposits: coarse “banded”, rich in chalcopyrite; massive, essentially pyritic and fine “banded”, rich in sphalerite and galena.
Several evaluation studies were recently developed for the Feitais, Moinho, Estação e Gavião deposits. To date, the following mineral reserves are known for Moinho and Feitais (JORC; cut-off: 1.5% Cu and 4.5% Zn):
Deposit ReservesTon Cu Cu Metal Zn Zn Metal Pb Pb
Metal Ag Ag Metal
(kt) (%) (t) (%) (t) (%) (t) (g/t) (oz)
Feita
is
CupriferousStockwork
Measured 348.9 1.98 6,902 0.27 946 0.07 240 8.06 87,428Indicated 3.559.0 1.72 61,343 0.28 9,796 0.06 2,133 7.46 825,399
Total 3.907.9 1.74 68,245 0.28 10,742 0.06 2,373 7.51 912,827
CupriferousMassive
Measured 508.4 1.65 8,401 1.57 7,963 0.46 2,344 0.00 0Indicated 2.797.6 1.78 49,701 1.41 39,513 0.36 10,050 0.36 31,258
Total 3.306.0 1.76 58,102 1.43 47,476 0.38 12,394 0.30 31,258Total 7,213.9 1.75 126,347 0.81 58,218 0.21 14,767 4.21 944,085
Moi
nho
CupriferousStockwork
Measured 84.3 1.79 1,509 0.75 630 0.24 199 14.86 38,942Indicated 137.4 1.52 2,092 0.65 887 0.22 308 11.09 47,930
Total 221.7 1.62 3,601 0.69 1,517 0.23 507 12.52 86,872Cupriferous
MassiveMeasured 1,232.6 1.68 20,695 1.32 16,326 0.45 5,498 0.00 0Indicated 1,909.2 1.50 28,648 1.41 26,878 0.53 10,069 0.53 31,318
Total 3,141.8 1.57 49,343 1.37 43,204 0.50 15,567 0.32 31,318Total 3,363.5 1.57 52,944 1.33 44,721 0.48 16,074 1.13 118,190
Total
Measured 2,174.2 1.73 37,507 1.19 25,865 0.38 8,281 1.87 126,370
Indicated 8,403.2 1.69 141,784 0.92 77,074 0.27 22,560 3.58 935,905Grand Total 10,577.4 1.69 179,291 0.97 102,939 0.29 30,841 3.23 1,062,275
MINERAL RESOURCES
OF PORTUGAL
41
Last figures for Gavião deposit are 12,3 million tonnes of inferred resources with 1,47 % Cu, 1,91 % Zn, 0,63 % Pb and 26 g/t Ag with a cut off of 1% Cu. The Algares deposit, which is currently exhausted, should have contained mineral resources greater than 50 Mt.
NEVES CORVO - This important mine is geological-ly situated at the end of the Neves Corvo - Rosário Anticline, a structure that runs NW-SE, the axis of which dips to SE, with deposits on both flanks (T.Oliveira et al., 1997). Various groups of sub-ver-tical faults occur which affect the mineral deposits and also low-angled overthrusts, related with rep-etitions of volcanic sedimentary and flysch units. These deposits are situated in the upper part of a volcanic sedimentary sequence (VS), mainly acid, and composed of three sequences of acid tuffs, separated by shales formations, with a discontinu-ous level of black shales immediately beneath the mineralised masses. Due to the abovementioned overthrusts, the flysch and volcanic sedimentary units repeat above the top of the mineral mass.
Geological, geophysical and geochemical pros-pecting work begun by the IGM (Portuguese Geo-logical Survey) and carried on by a Portuguese-French consortium (Sociedade Mineira de Santiago, S.M.M. Peflarroya and SEREM - BRGM) led to the drilling and intersecting in 1977 of the first deposit (Neves). Next, three more important deposits were discovered, Corvo, Graça and Zambujal, with a fifth deposit discovered in 1988 (Lombador). In 1980, the consortium gave way to Somincor (Sociedade Mineira de Neves Corvo, SA).
The mine has been a significant producer of copper since 1989 and in 2006 commenced treating zinc ore. The processing of zinc-rich ore was suspended in November 2008 pending an improvement in zinc prices and the zinc facility was converted to treat copper ore. Zinc production is expected to re-commence in 2011 or even this year. Mine access is provided by one vertical five metres diameter shaft, hoisting ore from the 700 metres level, and a ramp from surface. Production targets for 2011 are 77 000 tonnes of Cu and 6 000 tonnes of Zn, con-tained in concentrates.
These deposits are composed of lenticular masses of massive polymetallic sulphides, also containing stockwork mineralisation in the footwall host rock, and are distinguished from other Pyrite Belt de-posits by their high copper and tin contents and a highly metal zonation. This latter fact, related with the segregation of base metals, favours the division into copper, tin and zinc ores, as well as massive “barren” pyrite.
Three main types of ore occur:
a) “Rubané” - occurs at the top of massive sulphide masses, particularly at the Corvo orebody, and is composed of chloritic shales, siliceous shales and chert-carbonate breccia, with sulphide veinlets sub-parallel to perpendicular to the stratification and sometimes with tight lenses and bands of mas-sive sulphides. The sulphides contained here are mostly cupriferous.
b) Massive sulphides - composed of approximately 95% of fine grained sulphides, in which pyrite pre-dominates, followed by chalcopyrite, tennantite
MINERAL RESOURCES
OF PORTUGAL
43
Neves Corvo Mineral Reserves Category 000’s Cu Zn Pb Ag
Tonnes % % % g/t
Copper Proven 23,235 3.6 1.0 0.3 44
Probable 4,508 2.3 0.5 0.4 45
Total 27,744 3.0 0.9 0.3 44
Zinc Proven 19,361 0.4 7.1 1.6 67
Probable 3,769 0.4 8.0 12.1 64
Total 23,130 0.4 7.3 1.7 66
Neves Corvo Mineral Resources (inclusive of reserves)
Category 000’s Cu Zn Pb Ag
Tonnes % % % g/t
Copper Measured 37,621 3.2 1.2 0.4 49
Indicated 7,688 2.3 0.9 0.5 49
Inferred 28,490 1.8 0.9 0.4 40
Zinc Measured 61,252 0.4 6.1 1.4 59
Indicated 18,094 0.4 6.5 1.7 53
Inferred 32,985 0.4 4.9 1.2 55
The Mineral Resources are reported above cut-off grades of 1.0% for copper and 3.0% for zinc and the Min-eral Reserves at a cut-off of 1.4% for copper and 5.0% for zinc, but not for Lombador deposit, where for phase 1, a zinc cut-off of 6.0% was applied for Mineral Reserve reporting.
Those are today the resources/reserves defined for Neves Corvo:
44
In September 2010 a new copper deposit was dis-covered, Semblana, located approximately one kilometre northeast of the Zambujal orebody.
The Semblana Copper Deposit comprises two zones: A recently discovered, high-grade massive copper sulphide zone at the southern end of the deposit of 0.64 million tonnes grading 6.2% copper and 62 g/t silver, overlying a stockwork copper sulphide zone. This massive copper sulphide zone measures approximately 150 metres north to south and 100 metres east to west, and is open to the east and west for expansion.
An extensive stockwork-type copper sulphide zone of 5.94 million tonnes grading 2.6% copper and 20 g/t silver. This zone occurs as one continu-ous zone measuring approximately 700 metres north to south and 250 metres east to west. Given the wide current spacing of drill holes, the zone appears to be open to the east and west.
S. DOMINGOS - The sequence and characteris-tics of the mineral-bearing volcanic sedimentary complex (VS) in this area are poorly exposed and understood, their structural aspects being particu-larly complicated. The upper levels of the VS are covered by a fairly thin turbiditic sequence over-lain by Phyllite-Quartzite Group formations.
Nevertheless, a volcanic sequence composed of rhyolites, jaspers and diabases can still be ob-served in old works. This mine was extremely im-portant in the past, and in fact dates back to Ro-man times. Between, 1858 and 1966, the “Mason
and Barry Company” mined around 25 million tons of ore, by open-cast operations going down to a depth of 120m with additional underground work to a depth of 400m (Carvalho et al., 1971).
The ore was composed chiefly of massive pyrite with a maximum grade of 10% copper and 14% zinc-lead, and average grades of 1.25% Cu, 2-3% Zn and 45-48% S.
Given the occurrence of massive polymetallic sul-phides in the formations (Silurian volcanic sedi-mentary complex) surrounding the Morais and Bragança massifs, as well as several geological and metallogenetic similarities with the Pyrite Belt, it is our opinion that the Trás-os-Montes zone is worth investigating.
Nevertheless, the main target will still be the Pyrite Belt, in which exploration will continue to be car-ried out in zones characterised by (Oliveira et al., 1998):
Areas of high tectonic complexity, where bar-ren allochthonous terranes thrust over more recent geological formations with high mineral potential.
Structural alignments, in which the VS can be found at great depth beneath more recent Paleozoic Flysch formations in Baixo Alentejo.
Areas within the Sado River Tertiary Basin, where the VS can occur at depths ranging from a few dozen to several hundred metres beneath Ceno-Anthropozoic formations.
MINERAL RESOURCES
OF PORTUGAL
45
OTHER METALS
Tungsten and Tin
The existence of a tungsten and tin metallogenetic province on the Peninsula, which in Portugal over-lays the Galicia - Trás-os-Montes and Central - Ibe-rian Zones, has long been known. In this province,
gold and silver occur with a certain zonality at re-gional scale in relation to tungsten, hence the fact that the potential areas in these two groups of sub-stances sometimes coincide.
W/Sn
W
Sn
ACTIVE MINE
ORE DEPOSITOR INACTIVE MINE
50KM
S
1- CASTELÃO 2 - COVAS 3 - CARRIS 4 - BORRALHA 5 - BESSA 6 - ADORIA 7 - VIEIROS 8 - VALE DAS GATAS 9 - STª LEOCÁDIA10 - S. PEDRO DAS ÁGUIA11 - FREIXO DE NUMÃO12 - TUELA13 - MURÇÓS14 - MONTESINHO15 - RIBEIRA16 - ARGOZELO17 - CRAVEZES18 - LAGOAÇA19 - RIBA D'ALVA20 - S. MARTINHO21 - TAROUCA22 - ALMENDRA23 - AZEVO24 - REGOUFE25 - BEJANÇA26 - SERRA DE BOIS27 - NAVE DE HAVER28 - ARGIMELA29 - GOIS30 - PANASQUEIRA31 - MATA DA RAINHA32 - SEGURA33 - SARZEDAS34 - LAGARES
GEOTECTONIC UNITS AND MAIN W, Sn DEPOSITS
BRAGA
PORTO
VISEU
12
34
5
7 8
11
24
2627
28
2534
29 3031
3233
2123
22
13 15 16
14
20
12
910
1918
176
COIMBRA
CASTELOBRANCO
GUARDA
CENTRAL IBERIANZONE
MESO-CENOZOICMARGIN
BRAGANÇA
46
The most promising areas for the occurrence of large deposits correspond to various types of geo-structural settings:
a) Areas covered by monotonous schist series where the existence of non-outcropping granitic dome is presumed. An example of this is the Schist-Greywacke Complex situated to the south of the Estrela Mountain, and in particular the belt running E-W between Góis and the Spanish border, which covers the Góis, Panasqueira and Argemela mines. In this area, the main model is probably the Panasque-ira deposit: mineralised sub-horizontal veins related with a non-outcropping, partially greisenized, leu-cogranitic dome.
b) Structural alignments of regional dimension con-taining various types of Sn-W deposits and small outcropping or sub-outcropping dome of differenti-ated granitoids. An example of this is the extensive WNW-ESE alignment that runs from near Ervedosa, through the Tuela, Agrochão and Murçós mines, and then, after being rejected by the Vilariga fault, con-tinues eastwards towards the Ribeira and Argozelo mines in Trás-os-Montes area. The standard deposit type has not yet been fully defined but could be sim-ilar to that of Tuela, with vast stockwork zones with a high density of mineralised veins and remobilisation along strike-slip faults running subparallel to the re-gional structural alignment. For this deposit, 464 057 tones of measured and indicated resources were recently calculated for “Open Pit W”, with 974,86 tonnes of tin, with a grade of 2,10 kg//ton.
We shall not cover the tin contained in the poly-metallic sulphide deposits of the Pyrite Belt in this chapter as these occur in a completely different metallogenetic context.
The primary deposits or occurrences of W-Sn are for the most part either directly or indirectly linked with granites, with differing typology: aplite-peg-matites (Lagares de Estanho - Queiriga), intra and extra-batholithic stockworks (Bejanca-Vouzela and Fonte Santa - F. Espada à Cinta) and vein type. The latter are more common and account for most production of wolframite in the country (Goínhas, 1987).
They are generally found in contact metamorphic aureoles, sometimes a great distance from the granite outcrops, in which case it is assumed their relationship with fairly deep, non-outcropping gra-nitic domes (Panasqueira, Argemela, Góis, Borralha, Vale das Gatas, Ribeira, Argozelo, etc.).
Besides these examples, there is also the special case of the skarns with scheelite, formed by contact metasomatism, which - in accordance with the wall rock structure -some geologists divide into two types: stratoid (Cravezes-Mogadouro, Stª Leocádia-Armamar, S. Pedro da guias-Tabuaço, etc.) and vein type (most of the skams in the Castelo Melhor-Escalhão region, near to the River Águeda and the Spanish border, however the most important ones in the Escalhão - Barca d’Alva sector are from the stratoid type).
48
est given their small size. The most important of these, however, are Nave de Haver (Sabugal), Gaia (Belmonte) and, to a lesser degree, Bejanca (Vouze-la), Massueime (Pinhel) and Stª Eulália (Elvas), and Vale do Tâmega (Ribeira da Pena) alluvium, amongst others.
In relation to the skarns with scheelite, special men-tion should be made of the potential of the so-called Douro Scheelite Belt, which includes the whole of the area where the formations of the Schist-Greywacke Complex and the sintectonic granites make contact. This is situated to the north and south of the Douro river between the meridians of Freixo de Espada à Cinta and Régua. Besides numerous occurrences, several interesting deposits have also been recognised: Cravezes (Mogadouro), Stª Leocá-dia (Armamar) and S. Pedro da Águias (Tabuaço). At this last one, Colt Resources as recently defined in-dicated mineral resources of 760 kt at a mean grade of 0.58% WO3, which is the equivalent of 4,400 t of contained WO3; and inferred mineral resources of 1,330 kt at a mean grade of 0.57% WO3, which is the equivalent of 7,600 t of contained WO3 (cut-off of 0.3 % WO3 for both indicated and inferred resources).
Another zone or belt of interest from an exploration point of view located in a similar geological context is the so-called Trancoso-Figueira de Castelo Rod-rigo Belt.
In the Serra de Arga zone (Minho district) - besides the existence of tin-niobium-tantalum mineralisa-tion- small deposits of scheelite stratoid type occur in skarns, interstratified in Silurian formations and in relation with the post-tectonic granites of Vila Nova de Cerveira and Covas: Cerdeirinha, Covas, Lapa Grande, Argela and Cabração.
We have already referred to the production of tung-sten and tin concentrates, which reached maximum levels during the Second World War and the main producing centres. Of these, only the Panasqueira mine remains in operation. Here, in July of 2011 a to-tal of 18 257 969 tones of resources, with 4 156 835 MTU WO3 and a cut off of 10 kg/m2 were defined.
The mineralised zone consists of series of sub-hori-zontal quartz veins, which overlap and fill the joints of fractures occurring in schist rock. These veins vary in thickness from 1 to 150 centimetres, the average thickness of the veins currently being mined around the 30-40 cm mark.
Besides the main minerals being mined - wolframite, cassiterite and chalcopyrite - various other minerals oc-cur, such as sphalerite, topaz, apatite, fluorite, triplite, marcasite, siderite, arsenopyrite and muscovite, not to mention many others. The mine is in fact, famous for the occurrence of valuable collection samples.
MINERAL RESOURCES
OF PORTUGAL
51
SSE to NW-SE systems, pointing to a N-S maximum compression direction (Goínhas, 1987).
In the Beiras region, the largest and most produc-tive area for uranium, the granite is intersected by numerous dykes of basic rock.
In this region, the intragranitic uranium bearing veins can be any of the following types:
jasperized veins; quartz veins; basic rock veins; granitic breccia, sometimes with limonite;
In the equally productive Alto Alentejo region, in-tragranitic uranium deposits are of the quartz veins and granitic breccia types.
Jasper type deposits have a characteristic para-genetic association: quartz, hematite, sphalerite, pitchblende, pyrite, galena, ankerite, chalcopyrite and coffinite. The pitchblende dates from the late Hercynian.
Mineral occurrences of all the other types essential-ly consist of hexavalent uranium minerals (second-ary uranium minerals).
Support for uranium mineralisation in peribatho-lithic deposits, which also occur in the Beiras and Alto Alentejo regions, is provided by the forma-tions of the Schist-Greywacke Complex.
These deposits are also almost totally composed of secondary uranium minerals, with pitchblende fairly rare.
Although this type of uranium dissemination de-posit in metamorphic schists that contact with granite represents a very important percentage of total known uranium reserves, its genesis is contro-versial. Deposits such as Nisa (Alto Alentejo), Azere (Beira Alta) and Horta da Vilariga (Trás-os-Montes) are important examples of this type of mineralisa-tion.
Occurrences related with concentrations of soil-leached uranium have also been detected in the Western Meso-Cenozoic Margin.
Geologically favourable zones for prospecting ura-nium in Portugal are described below. These are or-ganised by their geological settings and in decreas-ing order of their potential:
Hercynian granites in known productive zones (Beiras and Alto Alentejo - CentralIberian Zone) and other interesting vein occurrences (gran-ites from the NE of Trás-osMontes, Galicia-Trás-os-Montes Zone and Évora Massif, OssaMorena Zone): - vein type deposits;
Metasediments from the Schist-Greywacke Com-plex and possibly from the Silurian, in particular in the contact metamorphism aureole (exo and endocontact) with productive granites in the Galicia -Trás-os-Montes Zone and the Central-Iberian Zone: - Iberian disseminated type depos-its;
Ampelitic and/or pyritic schists from the Paleo-zoic, in particular in the Ossa-Morena Zone: - dis-seminated type deposits in Silurian black schists;
52
Nepheline syenite from the Serra de Mon-chique: - deposits associated with alkaline in-trusions from the tertiary age;
Continental sediments from the Meso-Cenozo-ic age from the Western Margin and, possibly, from the Southern Margin: - sandstone type de-posits;
Sediments from inland Paleogene basins or from hydrographic basins of large rivers, partic-ularly in the cover zones of productive granites:
- sandstone type disseminated deposits.
In the Portuguese uranium metallogenetic prov-ince demonstrated reserves in the known deposits in the Beira and Alto Alentejo regions are around 8200 tons of uranium metal.
Today no mines are working, but recently several international companies showed interest in the Portuguese potential, specially in the Nisa deposit, where 2.5Mt with 0.11% U3O8 (cut off of 0.05%) of geological resources are estimated.
Although several deposits were exploited in the past, with a special relevance to Cercal mine, today the Moncorvo deposit, composed of 5 ore bodies, is the most important one. 30 years before the laboratorial tests showed that it’s technically possible to obtain concentrates with grades between 64% and 68% in Fe and 0,15% and 0,25% of P. More recently was
Iron and Manganese
concluded that it’s possible to reduce a little bit the grade in P, using selective mining works and through metallurgical methods we can reach to iron concen-trates with less of 0,10 % P. The proven and probable reserves of the Moncorvo deposit, with a total of 550 Mt of ore, are enough for produce 250 Mt of fine sin-terized agglomerates with 60% to 65% Fe.
Portugal occupies an important position in terms of lithium production. This is mainly due to the exploi-tation of aplite-pegmatite veins, rich in lepidolite, embedded in a late Hercynian granite, porphyritic, monzonitic, in the region of Gonçalo (Guarda).
Lithium-bearing lodes are characterised by a geo-chemical association of A1-Na-Ca-PRb-Li-B-Sr and occupy a system of sub-horizontal fractures running predominantly NS, with cassiterite, tantalite and
beryl also occurring.
Other potential lithium-bearing areas exist: the re-gion between the Barroso and Alvão mountain ranges. The main deposits (Alijó, Veral e Adagói) are associated with aplite-pegmatite veins, rich in spodumene, embedded in Silurian metasediments composed of micaschists and quartziferous schists with intercalations of black schists. with intercala-tions of black schists.
Lithium and High Tech Metals
MINERAL RESOURCES
OF PORTUGAL
53
As we have mentioned, the lithium occurs chiefly in the form of spodumene, but also in amblygonite and, more rarely, petalite, eucryptite and monte-brasite, the pegmatite facies clearly the richest in lithium.
The results of regional exploration have led to the re-connaissance of a large extension of the aplite-peg-matite field with spodumene, a NW-SE alignment of more than 20 km identified parallel to the 3rd stage of Hercynian deformation. This type of lithium min-eralisation is independent in space and in time from others of Sn-Nb-Ta and W, occurring in the zone.
In Alijó and Veral proven geological reserves of 586.560 tonnes of quartz, feldspar and lithium on the main vein, and more 600.000 tonnes of other veins, totalizing about 1 200 000 tonnes, were de-fined.
In Adagói proven reserves of 187 000 tonnes of ore were defined on the Lousas sector and 220 883 tonnes on the Gondiães one.
The Iberian Pyrite Belt is known as a relevant source of pyrite ores and associated base metal resources (copper, lead, zinc), having been extensively mined in the past. Its future potential may likely be in the mining of what have been up to now marginal ores and deposits for their high-tech element contents.
Recent sampling developed in a research project show significant contents of several elements with interest for a variety of high-tech applications.
Among the most remarkable results, whole-rock analyses have revealed anomalously high contents of:
Indium in ores from the Lagoa Salgada deposit, with 12 samples averaging 29 ppm In;
Selenium in ores from the Lousal mine and the Lagoa Salgada deposit, with 6 samples averaging respectively 48 and 81 ppm Se;
Germanium in remobilized vein deposits, such as in the Barrigão mine, with 10 samples averaging 61 ppm Ge.
The mineralogical and chemical characterization of Lagoa Salgada ores showed that indium is carried by excess-metal chalcogenides and spectroscopic studies using synchrotron radiation at the European Synchrotron Research Facility disclosed singularities of indium binding in the carrier phases. The valoriza-tion of indium content strongly contributes to the feasibility of mining Lagoa Salgada copper ores.
Selenium is found mainly in galena and sulphosalts.
Similarly, in Barrigão ores, germanium is present as sub-microscopic inclusions of a copper-tin-ger-manium phase within chalcopyrite and small vugs therein. Remobilized vein deposits like Barrigão con-sist of relatively narrow veins and their tonnages are rather small but several such deposits exist and ger-manium is potentially a relevant by-product in the processing of these ore types.
54
Rare Earths
Portugal’s geostructural characteristics lend it great potential for the occurrence of rare earths. This has been confirmed by mineralometric stud-ies and radiometric surveys.
With the exception of the Alter Pedroso zone, where hyperalkaline rocks have been investi-gated by an exploration company, this group of elements had never been prospected in Portugal until recently.
Regional exploration was carried out in the Beira Baixa and North Alentejo regions by the Geologi-cal Survey, involving geological mapping, alluvial and stream sediment sampling and radiometric surveys, the aim being the selection of targets to investigate at a later stage.
Prospecting is aimed at detecting Rare Earth bear-ing minerals, such as monazite - nodular monazite in particular - in sedimentary rock areas (more or less metamorphised) and xenotime, without over-looking other minerals such as apatite and allan-ite.
Mineralometric data on the North Alentejo sug-gests that, to date, nodular monazite rich in light rare earths has originated chiefly from the disinte-gration of the ridges of the Ordovician quartzites on the southwest flank of the Portalegre Syncline, even in the case of Reveladas (Marvão), where the alluvial samples were collected in the midst of the Silurian formations, but close to these ridges.
Normal monazite appears to be chiefly associated with granite, as is the case of the Fronteira granite and tertiary gravel, originated from it.
As far as the lithogeochemistry of the Ordovician is concerned, it is the radioactive quartzites in-terstratified in the schists immediately above the thick base quartzites that are rich in rare earths, and not the schists itself. This finding for the ra-dioactive quartzites, previously known in Alegrete (Portalegre), mapped in detail in the Vale de Cava-los area and also detected in Penha Garcia, goes against existing data on the levels of schists with nodular monazite, rich in rare earths, particularly europium, in other places of Europe and America.
The occurrence of these metals in Portugal has not been sufficiently investigated, although vari-ous metallogenetic scenarios point to their po-tential existence. These are briefly described be-low:
a) Morais and Bragança mafic and ultramafic mas-sifs, where in some sectors, like the Alimonde one, chromite-bearing peridotite formations (dunites) occur.
b) Évora Massif of the Ossa-Morena Zone. Parts of this area have geological and metallogenetic char-acteristics that are similar to those of the Água Blanca zone (Monasterio - Spain), in which an im-portant deposit of Ni was discovered.
c) Basic and ultrabasic complexes occurring on the north and south edges of the Ossa-Morena Zone, particularly in the Alter do Chão, Elvas and Campo Maior massifs and also in the Beja ophiolite complex.
Nickel, Cobalt and Chrome
56
Block Extraction in Marble Quarry
Marbles Marbles are mainly produced in the Estremoz an-ticline and represent approximately 20% of the to-tal production of dimension stones, in value. They have an historical background as they are being ex-ploited for 20 centuries. The pink type, named Rosa Puro, is the most valued.
Other areas, such as Viana do Alentejo, Trigaches and Ficalho, although small, produce very beautiful ornamental types with a variety of colours ranging from greenish and greyish to black and white.
In the anticline, at Borba, there is a technological centre (CEVALOR) for studying, evaluating and pro-moting dimension stones.
The present production of dimension stones is ap-proximately 2,857,000 ton from which about 48% is exported. Exportation has changed considerably in the last decade due to the increase in the value of the exported products: from the total exportation in 2010, 61 % were processed products, 24 % slabs and only 15% blocks.
Considering the production of dimension stones all over the world, Portugal has lost ground, but maintains on 2009 the 9th rank in the world, after Brazil and Spain.
All the Portuguese dimension stones have a desig-nation of origin to identify the place or region of the product, like a seal of quality related to its great aesthetic value.
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Ornamental granites (that includes similar rocks, such as slate, acid porphyry, serpentine, nepheline syenite, witch had a small production) represent the subsector with the highest growth rate in re-cent years, and the production achieved in 2010 puts it in the first place, ahead of the marbles and limestones, with 52% of the global value produc-tion (1,798,508 tonnes).
The global reserves of granites are very large and further detailed studies in some areas are needed.
The production of other ornamental rocks, such as slate, acid porphyry, serpentine, nepheline syenite and others is small. The reserves are small as well.
1.2 - Industrial Stones
All the above mentioned stones can have alterna-tive uses when they are not adequate for ornamen-tal purposes, the most common use being crushed stone for road building and construction and gra-nitic cobblestones for paving. Granite wastes have the highest rate of utilisation. There are however other important industries which depend on this type of resources. 1.2.1 - Use of Quarrying Wastes
From granites and similars
Granite wastes have the highest rate of utilisation. The most common use is the production of cobble-stones for paving. This use is an important subsidi-ary industry with a large incidence in foreign mar-kets. These wastes are also used for masonry and other purposes.
Limestones Limestones are mostly produced in Maciço Calcário Estremenho where several ornamental types occur. They are cream coloured and are differentiated by their texture. “Moca Creme”, “Relvinha” and “Semi Rijo” are the most known and valuable varieties. This region is also the main production centre of the typical “Calçada Portuguesa” – small white and black limestone handcraft cubes used for pedes-trian streets paving in many Portuguese towns and cities, which is becoming largely appreciated.
Greenish and pinkish breccia limestones are ex-ploited in the Algarve region.
Microcrystalline limestones are produced at Sintra and exhibit several colour patterns such as white, pink, yellow, red, blue and black. Their production is restricted and at a short-term will be mainly di-rected for the restoration of the ancient buildings and monuments of Lisbon.
The production of limestones in 2010 was about 791,705 tonnes and represents 27% of the global value production of dimension stones.
Granites Ornamental granites can be found scattered all over the country although with a higher density in northern areas such as Viana do Castelo, Braga, Viseu, Porto, Braga and Vila Real. In the South this type of granite occurs in Portalegre district.
They show a large diversity of textures and colours with predominance of greyish, being yellowish and pinkish types also found.
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Estremoz Marble
From marbles and limestones
Besides the most common uses, marbles and lime-stones wastes are also used in several industries, such as production of lime, agricultural correctives, ceram-ics, animal food, chemical industry, filler and others.
1.2.2 - Quarries for Industrial Uses
Dolomitic limestones
They are mined in several places in the country be-ing the most important producers those localised in Sesimbra and in Maciço Calcário Estremenho. Dolomitic limestones are mainly used for siderurgi-cal, glass and ceramic (refractory) industries.
Limestones
Limestones are mainly exploited as crushed stone for use in road, building construction, lime and ce-ment industries. The main production centers are located in the surroundings of Coimbra (Serra do Sicó), Maciço Calcário Estremenho, Alenquer, sur-roundings of Lisbon, Serra da Arrábida and Loulé. The annual production in 2010 was about 32 Mt.
Limestones in Portugal are also used in the paper in-dustry. This is a sector that has evolved very quickly and is now using a large space formerly occupied by kaolin. Due to their whiteness, low abrasivity, low cost and abundant reserves, oolitic limestones from Serra do Sicó and Maciço Calcário Estremenho are
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Via Vai Kaolin Mine
replacing kaolin as filler in the paper industry. Some wastes from very white marbles of the Estremoz An-ticline are also used in this industry.
Granites
There is a great number of places where granites
are exploited for crushed stone as raw materials for the road and building construction industries. Those places are mainly located in northern Portu-gal at Viana do Castelo, Vila Real, Braga, Porto, Vi-seu, and Guarda.
The production in 2010 was around 22 Mt.
2.1 - Ceramic Raw Materials
From all the Portuguese industrial minerals, ceramic raw materials play an important role as they supply an industry of great economical relevance.
Kaolin
Portugal is rich in kaolin for ceramic uses. The origin of kaolin in Portugal is geologically diverse includ-ing sedimentary deposits of different ages and pri-
2 - Industrial Minerals
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The producing areas are mainly distributed in the regions of Viana do Castelo, Braga, Porto, Aveiro, Co-imbra and Santarém. The known reserves are above 50,000,000 tonnes. There are still potential geologi-cal formations that need to be better studied.
2.2 - Feldspar
Traditional sources of this raw material used as a ce-ramic flux are associated to granitic pegmatites from which quartz and feldspar were separated by hand and nowadays also in a modern industrial unit of op-tical separation located in Mangualde.
mary deposits formed by hydrothermal processes and weathering of granites, gneisses and acid por-phyries. Arkoses have recently become a relevant resource due to their content in kaolin - besides k-feldspar and silica sands. The kaolin subsector has shown a great dynamism with the aims of increas-ing quality levels, diversifying uses and penetrating in foreign markets. Although Portuguese kaolin is essentially appropriate for ceramics it also plays a small role as filler and coating in the paper industry and as a filler in other industries.
Most of the total kaolin Production (285,000 tonnes in 2010) is used by the important Portuguese ceram-ic industry: sanitaryware, tableware, refractories and wall and floor tiles.
Bajoca Quartz and Feldspar Mine
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bricks, roof tiles, wall and floor tiles and other prod-ucts for construction industry. Some of these plants belong to important industrial groups but in gen-eral they are family companies. This is a sector which has progressively been modernized with advanced technologies. This modernization brought along an important evolution in what concerns the knowl-edge of the deposits, the control of the quality and the uses of the raw material.
Common clays occur mainly in the areas of Aveiro, Coimbra, Leiria, Lisboa, Santarém and Faro.
Due to their mineralogical and chemical proper-ties some clays are appropriated for manufacturing thermo swelling products used as insulators and for producing light bricks. These clays occur in the area of Ansião in Central Portugal where there is a mod-ern plant in operation.
The reserves of common clays are very important and they can supply the processing sector for a very long time. Besides the reserves already known there are extensive potential areas needing further stud-ies.
2.4 - Ball Clays
Ball clays are illite kaolinitic clays with mineralogi-cal, chemical and technological properties that al-low their use in porcelain, sanitaryware, glaze, floor and wall tiles. Ball clays supply a very important processing sector with high economical relevance mainly in terms of exportation.
The deposits are located in a restrict area on the central coastal zone of Portugal: Águeda, Anadia,
The progressive depletion of this kind of resource made it necessary to search for alternative sources. Presently feldspar is mainly obtained from aplitic and aplitic pegmatites and weathered moscovitic granites. After milling and purification these raw materials are used in the form of feldspathic sands.
The arkoses constitute another important resource in which, more frequently, K-feldspar occur in asso-ciation with kaolin and silica sands, some with high purity grade. The importance of these raw materials is growing due to the potential uses of arkoses by-products and huge reserves.
At Guarda and Vila Real some pegmatites containing lithium minerals (lepidolite and spodumene, respec-tively) are being mined as high quality ceramic raw materials.
The occurrences are mostly associated to granitic massifs that are located mainly in the area of Braga, Vila Real, Viseu and Guarda. Important arkosic de-posits occur in the region of Coimbra.
The total production of feldspar and feldspathic sands is about 170,000 tonnes.
The potential of Portugal for ceramic products is very large and there is the opportunity for the coun-try to become a great exporter.
2.3 - Common Clays
Common clays are very abundant and they are pre-dominantly distributed in the western and southern mesocenozoic coastal zone. There are many pro-cessing plants dispersed by those zones producing
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The reserves are very large distributed in eolian, flu-vial and marine Pliocene deposits from which the more important are situated in the areas of Figueira da Foz, Marinha Grande, Pombal, Leiria, Alenquer, Santarem, Rio Maior and Setubal.
Other source of silica sands is associated to the ex-ploitation of kaolin as a byproduct.
The present production is around 1,1 Mt.
2.6 - Talc
Talc is a raw material presently in great demand in ceramics besides its use as filler in many industries, such as paper, paints and rubber.
Talc deposits occur in the Bragança and Morais ul-trabasic and basic massifs in Trás-os-Montes being the reserves not large.
Due to the contamination mostly by iron oxides and chromite, portuguese talc presents greyish and yel-lowish colour and shows a medium level of quality grade, needing a beneficiation process by magnetic separation. Portugal imports talc for more exigent uses.
The annual production is about 11,980 tonnes.
2.7 - Other Industrial Minerals
2.7.1 - Gypsum
Portugal is self sufficient in black gypsum to sup-ply the cement industry and agricultural uses. The output of white gypsum, some with high grade of
Redinha, Pombal and Barracão. Although, explora-tion efforts by private companies are being con-tinuously made. Within this field of the ceramic raw materials the ball clays subsector is the more advanced in what concerns the knowledge about the deposits, extraction technologies, homogeni-zation, quality control and rational utilisation of re-sources. In order to meet these requirements a care-ful and very selective exploitation and a continuous chemical, mineralogical and technological control are needed in the quarrying process. With this aim the companies are being equipped with their own laboratories. A plant of atomisation is already estab-lished representing an important advance within this subsector.
Some of the ball clays with low quality are used as agglutinants in the production of animal feed, sup-plying the whole domestic market and also being exported.
It is worth mentioning the fact that this is a pioneer subsector in the environmental recovery of exploit-ed areas.
2.5 - Special Sands
Special sands are very pure silica sands, in general very well sorted.
They have usually a small content of kaolin (up to 6%) and heavy metals. After a process of purifica-tion that can include washing, classification, mag-netic separation and flotation they are used in ce-ramics, glass, including crystal glass, and foundry. They are also used in other industries in the form of powders.
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unities supply mainly the chemical industry and also for deicing. Only a small amount is used in food in-dustries.
The potential for salt rock production is large in as-sociation with extensive diapir zones in the west and south coastal zones.
The production is about 618,960 tonnes.
2.7.3 – Barite
Portuguese barite occurs on the north of Portugal, near Bragança. It’s a relatively inert mineral with a high density and the primary ore of barium. This material is frequently used as a weighting agent in drilling muds and also like a pigment in paints and in hospital facilities because is opaque to x-rays. The production in 2010 was a little bit more than 15 tonnes.
brightness is small and there is the need to import large amounts, uncalcined and calcined, for wall-board, plaster, pharmaceutical, ceramics (mould), hydraulic lime and other uses.
The main producing areas are Soure, Óbidos and Loulé.
Annual production is about 336,750 tonnes.
The reserves are large but there are potential areas needing further detailed studies.
2.7.2 - Salt Rock
There are several diapir zones in Portugal from which three areas are in production: Matos do Car-riço (Figueira da Foz) and Matacães (Torres Vedras), where salt is extracted by solution, and Loulé, op-erating by underground mining. These extracting
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The legal framework governing activity involving the prospecting, exploration and exploitation of geological resources was entirely modernised as from 1990 with the publication of Act nº 90/90 of 16th March which defines the main provisions con-cerning the discovery and exploration of geological resources (with the exception of oil). This regime is regulated by six other Acts published on the same date, specific to each type of geological resources:
ore deposits (Act nº 88/90);
hydro-mineral resources (mineral and mineral-industrial waters - Acts nºs 86/90 and 85/90);
geothermal resources (Act nº 87/90);
mineral masses or quarries (Act nº 89/90), that was later changed by the Act n. 270/2001 with the text of the Act n. 340/2007;
and spring waters (Act nº 84/90).
In accordance with this legislation and as a result of Constitutional requirements, the following geologi-cal resources are State owned:
ore deposits (including all metallic and radio-active ores, coal, graphite, pyrites, phosphates, asbestos, talcum, kaolin, diatomite, quartz, feld-spar, precious and semi-precious stones, potas-sium salts and rock-salt);
hydro-mineral resources (natural mineral waters and mineral-industrial waters);
geothermal resources.
The remaining resources, as follows, are not State owned and may be privately owned: mineral masses (clays, limestones, marbles, gypsum, granites, sand and in general all the ornamental stones and those used in building not included under the ore deposits category) and spring waters.
Mineral licensing will generally follow in the wake of an application submitted by the applicant for the granting of one of four different mineral licenses in accordance with the type of activity to be undertak-en and the type of resource, depending on whether or not it is State owned:
administrative prospecting and exploration con-tract;
administrative mining contract;
In both cases covering certain resources within those which are State owned (ore deposits, and hydro-mineral or geothermal resources)
quarry operating licence in respect of mineral masses; and
spring-water operating licence.
Applications for prospecting and exploration con-tracts and mining contracts are addressed to and decided by the Minister for the Economy, Innova-tion and Development (MEID) (or by his Secretary of State for Industry and Development (SEAID)), sub-mitted to and processed by the Directorate-General of Energy and Geology (DGEG) which will also moni-tor the exercise of the operations covered by the contracts.
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landscape reconstruction, protection and safety, there are additional specific regulations concerning these matters ( noise, dust, underground waters etc,) and specialised departments that supervise their application.
In accordance with the provisions of the law, if the environmental impact assessment (where required under the law) is refused by the Minister of Environ-ment the mining licence should not be granted.
If so requested, DGEG may provide technical and ad-ministrative advice concerning the drawing up and submission of the applications, providing drafts and models, information concerning available areas or those licensed, and may allow consultation of tech-nical documentation and maps in the archives. The prospecting and exploration contracts and mining contracts usually follow the form of existing models.
The following summarise the principal features of these two administrative contracts, the regime of which is governed by law.
Spring-water operating licence applications are pro-cessed and decided by DGEG.
Applications for quarry operating licences are pro-cessed and decided by the Regional Delegations of the MEID (DREs) or by the Municipal Authorities, depending on whether the operations are medium/large or small scale.
In processing these mineral licenses other depart-ments of the Administration involved in the envi-ronment and spatial planning are consulted as are the municipal authorities of the area covered by the application. These entities are also responsible for monitoring the matters indicated. The DREs are re-sponsible for inspecting quarry operations.
Although mineral and environmental legislation contains imperative provisions concerning the as-sessment of the environmental impacts of the ac-tivity (mandatory for all operations located in areas of protected landscape identified in the law and for operations covering more than 5 hectares or with a production volume grater than 150,000 tonnes),
Prospecting and Exploration Contracts
Prospecting and exploration rights cover the miner-als specified in the contract and the area set forth therein (which, save exceptional cases, may not ex-ceed 1,000 km2).
The total duration of the contract, including proro-
gations, should not, usually, exceed 5 years (3 years in the case of hydro-mineral and geothermal re-sources). Contract periods are negotiable and usu-ally include an initial period of 1 to 2 years followed by 3 or 3 one-year extensions, if consistent with the minimum work programme and budget. With the exception of those areas in respect of which a min-ing contract application has been lodged, the Licen-
Prospecting and Exploration Contract, and Mining Contract Regime
68
exploration contract provided that the Licensee is not at fault with regard to compliance with legal and contractual obligations, provided always that an application is submitted to the effect, before the prospecting and exploration contract ends, ac-companied by the necessary information (including presentation of a mining plan compatible with good mining practice and with environmental protection requirements).
The prospecting and exploration contract also con-tains provisions concerning the duration of the op-erating contract and the payment of a royalty (usu-ally a percentage of sales F.O.B./Mining area).
Cancellation of the prospecting and exploration contract resulting from non-compliance with legal or contractual obligations is subject to the rules and procedures established by law. Renunciation of rights or complete abandon by the Licensee of the area under concession is allowed provided that the Licensee’s commitments have been complied with or that the justification submitted is accepted.
Assignment of prospecting and exploration rights is subject to the prior consent of the Minister follow-ing an application lodged by the Licensee, accom-panied by information concerning the capacity of the intended Licensee to continue operations and to meet contractual commitments, particularly those in respect of the schedule of work and investment which must be up to date.
Occupation of land to set up the prospecting and exploration work shall be preceded by the consent of the owners of the land in question, which, if re-fused without due grounds, may be granted by the courts at the Licensee’s request.
see should abandon a part (usually 50%) of the area contracted for on the occasion of each prorogation to the prospecting and exploration contract.
The contract stipulates the general work pro-grammes and minimum investments as agreed in advance, to be implemented by the Licensee over the duration of the contract in question (balances of investments made larger than the established minimum figures established for a given contract period may, however, be carried forward to the next period). The general schedule is complemented every year by detailed programmes and the respec-tive budget. They are monitored via presentation of half-yearly progress reports the last of which should be drawn up as the final report of the work and in-vestments undertaken, presented together with the main conclusions.
The reports and technical data provided by the Li-censee are considered confidential during the dura-tion of the contract.
Non-compliance with these minimum commitments may lead to refusal of prorogation or to cancellation of the contract by decision of the Minister after prior notice to and consultation with the Licensee..
The contract also stipulates payment of an annual mining rights surface fee, fixed or variable, in pro-portion to the size of the area granted (€/km2). The nature and amount to be stipulated are negotiable.
Pursuant to prevailing legislation, the Sate, in the event of a commercial discovery, guarantees the granting of a mining concession (involving entering into a proper contract) in respect of the resources discovered within the scope of the prospecting and
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and the suspension may not last longer than au-thorised, unless renewal thereof shall have been requested and granted, if justified.
Unauthorised suspension of mining operations may lead to cancellation of the contract if the Li-censee, following a reasonable period of notice, shall not have put an end to the suspension or presented acceptable justification.
Cancellation of the contract for non-compliance with legal and contractual conditions is subject to the rules and procedures established by law.
The contract also stipulates annual payment of a royalty, generally in the form of a percent-age of the values of the F.O.B./Concession sales. Conditions governing the periodic review (usu-ally every 5 or 10 years) of this percentage and its suspension or reduction whenever justified to ensure continuation of operations are also gov-erned by the provisions of the contract.
Assignment of mining rights is subject to the pri-or consent of the Minister, as mentioned above in connection with assignment of prospecting and exploration rights.
The Licensee is entitled to apply for expropria-tion for public service of the land necessary to the mining operations in the event that agree-ment cannot be reached with the respective land owners.
The concession contract entitles the Licensee the sole right to exploit the specified resources within the area set forth in the contract. The du-ration of the contract is stipulated on the basis of the estimated duration of the resources un-der normal operating conditions in accordance with the geological report, preliminary feasibility study and mining plan submitted together with the application. It covers an initial period and 1 or 2 prorogations.
Mining operations shall proceed in accordance with a general plan of work approved or revised (as necessary) and with yearly work programmes, and in a manner consistent with applicable reg-ulations and good mining and environmental practice. For operations larger than 5 hectares or 150,000 tonnes (and all scale of operations if lo-cated in areas of protected landscape identified in the law) an environmental impact assessment and a protection plan must be submitted to be approved by the Environment Ministry as a condi-tion for the award of the contract. In accordance with the provisions of the law, if the environmen-tal impact assessment is refused by the Minister of Environment the mining licence should not be granted.
The Licensee shall appoint and register the tech-nical manager in charge of the mining operations.
Notice of suspension of mining operations must be given to the Minister and consent obtained,
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70
plication and negotiation of the contract.
For non-residents to carry on mining activity (or any other activity) in Portugal several formalities must be complied with, including:
_ commercial registration of the permanent establishment to be set up (usually in the form of a branch) or the incorporation of a lo-cal company in accordance with the provisos of the Companies Code.
_ This permanent establishment must be set up if the activity to be undertaken lasts for more than one year;
_ registration of the investment with AICEP - (Agency for Investment and External Com-merce of Portugal).
Mining companies are subject to the tax regime applicable to commercial and industrial activity as a whole, including the IRC Code (Corporation Tax Code). Tax law allows an annual provision to be set aside into a fund to pay for future expense incurred in implementing the landscape and en-vironment recovery plan of the site of the opera-tions.
As in any other industrial activity, exploration and mining operations may be undertaken by natu-ral persons or bodies corporate and, particularly, by companies, the latter being the form usually adopted by operators.
Applicants for prospecting and exploration li-cences and mining licences must, in accordance with legislation, submit together with their appli-cations full identification and other information confirming their technical and financial capaci-ties and their experience in the operations they intend to undertake.
Applications shall also include, as applicable, a prospecting and exploration work programme and the respective budget, or a mining plan. Fol-lowing submission of a properly drawn up appli-cation the candidate is invited to present a bank guarantee, designed to ensure pre-contractual good faith (the guarantee to be returned to the candidate as soon as the application is accepted or rejected by the Minister). There follows ne-gotiation of the contract and the publication in the press of notice of the application so that any claims may be lodged within 30 working days.
With regard to the candidature of non-residents a local agent should be appointed to simplify con-tacts with DGEG during the processing of the ap-
Doing Business in Portugal
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CARVALHO, D., GOÍNHAS, J A.C, e SCHERMERHORN, L.J.G. (1971): Principais Jazigos Minerais do Sul de Por-tugal. Livro Guia da Excursão n° 4 do I Congresso Hispa-no-Luso-Americano de Geologia Económica, Direcção-Geral de Minas e Serviços Geológicos, Lisboa.
CARVALHO, D. (1994): Passado e Futuro dos Recursos Minerais em Portugal. Rev. Colóquio/Ciências, n° 14, Fundação Calouste Gulbenkian, Lisboa.
GOINHAS, J. (1987): Cadre géologique et métallogé-nique des ressources minières du Portugal. Chron. rech. min., 489, p. 25-42.
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MATOS DIAS, J. M. and SOARES DE ANDRADE, A. A. (1970): Portuguese uranium deposits. Mem. e Not. da Univ. Coimbra, n° 70, p. 1-22.
OLIVEIRA, J.T., PACHECO, N., CARVALHO, P. and FERREI-RA, A. (1997): The Neves Corvo Mine and the Paleozoic Geology of Southwest Portugal. Geology and VMS De-posits of the Iberian Pyrite Belt, SEG Neves Corvo Field Conference 1997, Guidebook Series, Vol. 27, p.21-71,
Society of Economic Geologists.
OLIVEIRA, V., MATOS, J., SILVA, M„ BENGALA, A., SOUSA, P, TORRES, L., MARTINS, L. e BORRALHO, V. (1998): Breve retrospectiva sobre a prospecção de sulfuretos polime-tálicos no sector português da Faixa Piritosa Ibérica. IV Simpósio Internacional de Sulfuretos Polimetálicos da Faixa Piritosa Ibérica, Lisboa.
QUESADA, C. (1992): Evolución Tectónica dei Macizo Ibérico (Una historia de crecimiento por acrecencia suc-esiva de terrenos durante el Proterozoico superior y el Paleozoico). Paleozoico Inferior de Ibero-América, Uni-versidad de Extremadura.
RIBEIRO, A. et al. (1979): Introduction à la géologie gé-nèrale du Portugal. Serviços Geológicos de Portugal da Direcção - Geral de Geologia e Minas, Lisboa.
SILVA, J.B., OLIVEIRA, V., MATOS, J. and LEITÃO, J.C. (1997): Aljustrel and the Central Iberian Pyrite Belt. Geology and VMS Deposits of the Iberian Pyrite Belt, SEG Neves Corvo Field Conference 1997, Guidebook Series, Vol. 27, p. 73 - 124, Society of Economic Geologists. SOCIETY OF ECONOMIC GEOLOGISTS (1997): Geology and VMS Deposits of the Iberian Pyrite Belt. Guidebook Series, Vol. 27.
VIEGAS, L. e MARTINS, L. (1992): Notas sobre a prospecção do ouro em Portugal. Estudos, Notas e Tra-balhos, DGGM, t. 34, p. 95 - 106, Porto.
KEY REFERENCES
ACKNOWLEDGMENTS
Laboratório Nacional de Energia e Geologia, I.P. (LNEG)
Contacts:
Direcção Geral de Energia e GeologiaAv. 5 de Outubro, nº 87 | 1069-039 LisboaTel.: (351) 217 922 700 | 217 922 800Fax: (351) 217 939 [email protected]
